Kiln DynaTrol Control Error Codes

strict warning: Only variables should be passed by reference in /home/hotkilns/public_html/sites/all/modules/captcha/ on line 61.

Search Knowledgebase

Knowledgebase FAQ

  • See the Sales FAQs for Frequently Asked Sales and Preorder Questions
  • The Knowledgebase is organized into a series of questions and answers having to do mostly with technical troubleshooting and understanding of kilns.
  • Although we write this for our own kilns many of these articles apply to other makes - although L&L takes no responsibility for that.
  • Many Knowledgebase articles have Actions, PDFs and Videos associated with them.
  • Actions are specific actions for you to take during the troubleshooting or repair process.
  • Each Action may also have Videos and PDFs associated with it and, in addition, specific Cautions.
Kiln DynaTrol Control Error Codes

This is a list of all Error codes for the DynaTrol

Note: Many of these error codes have an ‘Err’ prefix rather than an ‘E-‘ prefix on kilns made before Jan 2006.

Some of these errors will only be detected if error codes setting is turned ON:

  1. E- A (E-A, EA, ErA, Er A, or Error A)is the result of having too high a number programmed into one or more of the segments of the Vary-Fire program you are trying to fire.
  2. E- d (E-d, ErrD, ED, ErD) – One of the thermocouples' temperatures is 50°F above traveling set point.  (Also see what it says under E- 9 below concerning proper setting of thermocouple circuits)
  3. E- 1 (E-1, Err1, E1, Er1) - Kiln temperature increasing slower than 12°F per hour when ramping for 22.5 min.
  4. E- 2 (E-2, Err2, E2, Er2) - Kiln temperature 50°F above hold temperature (18 seconds).  If this a cooling segment, try using a cooling rate of 400°F or 500°F rather than one that is faster.  Loose and overheated TC connections/ wires or old thermocouples can cause this too. Sometimes happens on an empty kiln during a first test firing.
  5. E- 3 (E-3, Err3, E3, Er3) - Kiln temperature 50°F below hold temperature (18 seconds). Pretty rare. Usually seen if heat treating metal and adding or removing parts at a higher temp (heat-treaters typically will turn the error codes off). Extremely uneven loading or something touching a thermocouple could cause it. Make sure your shelves are not blocking heat transfer between the zones (stagger shelves if you can). Usually E- 1 will appear first from a slow firing kiln as the kiln will slow itself and not move into the hold until all the thermocouples are reasonably close to the hold temp. Loose or overheated thermocouple connections/ wires or old thermocouples can cause this too. Can also be caused by programming a ramp rate that is too fast for the capacity of the kiln. Check to make sure relays are connected to the proper outputs. Check that thermocouples are connected to the proper inputs.
  6. E- 4 (E-4, Err4, E4, Er4) - Kiln temperature 50°F above previous hold when ramping down (18 seconds). Try using a cooling rate of 400°F or 500°F rather than one that is faster. Loose and overheated thermocouple connections/ wires or old thermocouples can cause this too.
  7. E- 5 (E-5, Err5, E5, Er5) - Kiln temperature 50°F below traveling set point when ramping down (18 seconds). Pretty rare.  Loose or overheated thermocouple connections/ wires or old thermocouples may cause this.
  8. E- 6 (E-6, Err6, E6, Er6):
    reversed thermocouple leads or a negative (very cold) temp reading. If the all the thermocouples are hooked up right, AND you are still getting negative readings, AND the Board Temp is reading negative too, replace the board (From IDLE press OTHER again and again until it says “bdT”, press ENTER to see the board temp)

These error codes can come on even if error codes setting is turned OFF:

  1. E- 20 (E-20, E20, Er20): did not receive lock on Clock Generator Module- try again or replace board.
  2. E- 21 (E-21, E21, Er21): on-chip a2d (analog to digital) not responding/problem- try again or replace board.
  3. E- 22 (E-22, E22, Er22): off-chip a2d (analog to digital) not responding/problem- same as E- 6  on boards made after Jan 2006. With the display saying IDLE press 1,2,3 to see which thermocouple is reading oddly- really low or a negative number. Check thermocouple wires at their connection points to be sure that red is going to “-“ and yellow to “+”. If all seems well, the problem is probably that the thermocouple itself is flipped over/ reversed in the thermocouple connection block. Just pull the thermocouple out of the kiln wall and remove it from the thermocouple connection block, flip it over, reconnect it to the thermocouple connection block and re-install it in the kiln wall. See this link for thermocouple polarity.
  4. E- 23 (E-23, E23, Er23): SPI not responding/problem- try again or replace board.
  5. E- 24 (E-24, E24, Er24): EE access while in write cycle- try again or replace board.
  6. E- 25 (E-25, Er25, E25): a2d (analog to digital conversion) not responding during power up- try again or replace board.
  7. E- 26 (E-26, Er26, E26): a2d (analog to digital conversion) not working properly/problem- try again or replace the board.
  8. E- E (E-E, EE): EE miscommunication or failure- try again or replace board
  9. E-bd (Erbd):  Bad board temperature. It usually will read very high- like 300°F at room temp (From IDLE press OTHER again and again until it says “bdT”, press ENTER to see the board temp).  This may mean that there is too much heat in your kiln room on near the kiln. Try cooling off the panel with a small fan or getting more ventilation in the room. Try firing again. Sometimes this is an indication of a bad board that needs to be replaced (especially if it is obvious that the board temperature is not that hot.) Note that there is an "alarm" setting for this (factory set for 250°F). This can be changed as one of the settings in the "hidden menu".
  10. E- /: division by zero detected- try again or replace board.
  11. E- - (Err-): power loss during EE write- try again or replace board.
  12. E- R (E-R, ErrR, ER): ram and EE do not match- try again or replace board.
  13. E- A (E-A, ErrA, EA): invalid program variable- try again or replace board.
  14. E- 0 (E-0, Err0, E0): software error- try again or replace board.
  15. E- 8 (E-8, Err8, E8): if cone fire temperature decreasing in last segment- a relay or an element has just failed. Loose or overheated power wires or connections and/or thermocouple connections or wires or old thermocouples can cause this too. Basically something has happened that stopped the power getting to one or more of the sections at the end of the firing.
  16. E- 9 (E-9, Err9, E9): wrong thermocouple hardware/software setting- rarely the board, only on ones made after Jan- ’06. Means the thermocouple circuit type (S or K), the S or K jumper setting on the back of the board, and/or the internal menu S or K setting do not all match. Start with the thermocouple circuit; wires and thermocouples must match, so determine whether are they S or K. Then check the S or K jumper setting on the back of the board. (Located approx center of the board under the marking “R97”. The tiny black plastic coated jumper only touching one of the prongs it is set to K. If it's touching both prongs it is set to S). Be sure the jumper setting matches the type of thermocouples they have. Then check the setting in the menu (from IDLE press OTHER/ 4/ 4/ 3/ then OTHER again and again until it reads TYPE. Press ENTER and any number key will toggle it from K to S to K, set it to the Type of thermocouple they have and press ENTER. Try running it again- still E- 9, replace the board (this is rare to have to do). See this link for a photo and more.
  17. E- U (E-U): invalid user number - try again or replace board
  18. FAIL alternating with TC1, TC2 or TC3: Generally this is a failed thermocouple. The TC+ a number indicates which position (TC1=top, TC2=middle and TC3= bottom zone).
    1. (Pre-Jan ’06 boards often read this when they are turned on, press ENTER to get them to IDLE.)
    2. If the code is a solid E- P, ErrP, or PF it means a longer power outage, that the program is off and kiln is cooling- restarting is usually OK except in complex multiple ramp programs.
    3. If it is a flashing E- P, ErrP, or PF it means the program is still running and that the power was just off for a few seconds.  If the power interruption is brief, the kiln will continue to fire when power is restored; in this case, there will be no indication of a power failure.  
    4. Press ENTER to clear the error code.
  19. PF, E- P (E-P), ErrP: error in the power supply.
  20. tC-- : The red and yellow thermocouple extension wires are reversed.
  21. L7KH (or something that looks like that): This is not an error code. It is the software version in the control. It will flash briefly on the screen when you first turn the control on.
  22.  STUC (stuck) indicates a key is not releasing.  The outputs are turned off and stop the firing if in progress.  It can be caused by moisture or stretched plastic from age or possible air bubble under the overlay.  Sometimes heating gently with a hair dryer will remove the problem temporarily.
  23. ROR - Not an error code. This just stands for Rate of Rise. You might see this in conjunction with a E-1 error code.


  1. Can you restart the kiln after an error code?
  2. What is the worse that can happen after starting up from an error code?
  3. How and Why to Turn Off Error Codes
  4. Error Codes for the One-Touch Control

Additional Actions to Take

  1. Unplug kiln or turn off circuit breaker if the kiln is wired direct to your power supply. If you can not physically be sure the power is disconnected (for instance is you see that the cord is unplugged you KNOW there is no power coming into the kiln) then check the voltage at the power connection pluck with your multi-meter.
  2. Unplug kiln.
  3. Open up the control panel. This will be a little different on each kiln series.
  4. Remove or open the panels that cover the element connections.
  5. Look at internal wiring.
  6. Specifically look at wires going from power connection block to the on/off switch, then to the control fuse, and finally to the control transformer.
  7. Make sure all wires inside control panel are connected.
  8. Look for any burned spots or deteriorating wire.
  9. Look for any short circuits. This might be caused by a wire losing its insulation and touching another component for instance. Typically if there are any short circuits there will be some evidence of a burn on the metal the wire touched.
  10. Look for dirt or foreign material. Some material can be an electrical conductor and could cause a short circuit. Clean out any dirt.
  11. Check all power wires for firm connections.
  12. Pull off and reseat all spade connector connections of power wires to remove oxides and ensure good connection.
Your power relays are one of the most important components in your kiln. They execute the will of the computer controller, giving power to the elements only when requested. These power relays are also mechanical switches which will wear out over time. Worn out relays can be the cause of slow or incomplete firings, error codes (E-1, E-d), etc. Other more obvious signs of relay failure are if a zone is lagging behind in temperature considerably or if you notice an entire ring of elements not heating/glowing. 
The surest way to test your relays is by using a multimeter to check input, output, and signal voltage. If you do not have access to a multimeter you can run a paper test, which will give you some indication of whether or not you have a relay out.
Paper Test: &
Here we will go through the process of testing relays and contactors as well as what to make of any test results. 
  1. Another way to check the relays (or bad elements) is to check the temperatures of each zone by pressing "1", "2" and "3" in sequence and recording the temperatures of each thermocouple at intervals over the length of the firing. If one zone is consistently firing at a lower temperature then you probably have either burned out elements or a bad relay.
  2. If the relay does not make a soft clicking noise when the kiln is turned on try turning the kiln off and on and then restarting the program.
  3. Remove panel.
  4. Set your multi-meter the approximately 24 volts AC. Check the voltage coming into the coil of the Power Relay. You can tell which wires these are because they will be the small wires coming from the control. This test will tell you if you are getting power to the relay coil which actuates the relay. Unless the relay is actuated by the control you will get no output from the power side of the relay.
  5. With panel plugged in and firing check output from Power Relay with your digital multi-meter. The meter should be set to the next highest voltage above 240 volts AC. Output should be approximately the rated voltage of the kiln when it is supposed to be calling for power to the elements.

CAUTION: LIVE ELECTRICITY IS INVOLVED WITH SOME OF THESE TESTS. This test should only be done by an experienced person familiar with electricity.

See this video:

  1. Carefully examine thermocouple tip. This is the exposed welded joint at the end of the thermocouple that is not covered up by the ceramic tube.
  2. To do this you will have to remove the thermocouple from its protection tube (if it is a kiln that has one of our protection tubes). You can do this with the kiln disconnected from power.
  3. Look for corrosion - especially if it severe. These thermocouple tips will oxidize and otherwise corrode over time. That is normal. There is some point, however, at which the corrosion affects the ability of the tip to work (thermocouples work by generating a small voltage at the tip caused by two different metals reacting to each other).
  4. Make sure the two wires are securely joined. One of the things that can cause an intermittent problem is a bad weld. If the two wires touch each other (even if they are not welded) they may work temporarily. However, if the weld is not secure then the wires could separate when the kiln heats up and cause an intermittent failure.
  5. If the thermocouple tip looks healthy then test the control board.
  1. Look for the nameplate data. Plug the amperage and voltage labeled here into Ohm's Law to see what the resistance for the whole kiln should be. If the nameplate is missing you can email the factory to try and figure out what model it is. Measure the inside dimensions of the kiln, take whatever resistance readings you can, let us know whether it has Hi-Med-Low switches on infinite type switches and describe anything else you can about the kiln. An emailed digital picture can be very helpful.
  2. Measure the total resistance of the kiln. Unplug the kiln or turn off the power if you cannot unplug it when measuring resistance in these circuits. Now turn all switches to high, and turn the kiln-sitter on. Measure the ohms from the prongs on the main power cord–-from the two "hot" blades, not from the ground or neutral. If there is a reading, it should be within 9% of what was calculated with Ohm's Law. The resistance can only be lower than what the nameplate calculations would indicate if the wrong elements were installed in the kiln or the elements are so old that they are squashed into each corner all the way around the kiln. Look for overheated connection if low resistance continues for any length of time and replace elements immediately
  3. Measure the resistance of each branch circuit. Turn the switches OFF. The switches must be off or the meter will read all the branch circuits at once. Measure branch circuit resistance with the kiln power OFF from the two flat prongs (not the ground) of the plug-heads of each kiln section. On other kilns you want to determine how many elements are in each circuit and how the elements in each circuit connect together and to each circuit's power wires. Take the branch circuit resistance reading at the point where the power wires connect to the element(s).
  4. Determine series or parallel. Look to see if the elements are wired in series or in parallel with each other. Even in L&L's latest kilns you would still have to either take the element box off or look at the kiln's wiring diagram to determine this.
  5. Check individual element resistance. Try to get a single element's resistance reading by either calculating it if they are in parallel or by measuring it with the meter if they are in series. You may need to disconnect wires to isolate as much as possible of each element.
  6. Take a voltage reading in each branch circuit at either the element connection to the power wires or at the control box receptacles on later L&Ls. Measure the voltage at the main power supply. If there is a considerable voltage drop from the main power supply to the element connection to the power wires then there is a corrosion or connection problem. Badly corroded connections need to be replaced immediately. Both parts of the connection should be replaced at the same time. Check your plug and receptacle connections, especially the main power cord and receptacle.
  7. If the measured resistance is slightly more than 9% over the calculated resistance and this correlates with the problem (slow kiln), you should ideally replace all the elements, or at least those with readings that are too high. If you do not replace them all at once the kiln may heat unevenly (this is much less of problem with kilns having the zoned design with ungraded elements rather than with kilns that have graded elements.
  8. If all of the element resistances are fine but the resistance of the whole kiln is not, the problem must be in a branch circuit. 
  9. With the kiln on, run a voltage test on the receptacles or at the connections to each element in each branch circuit to see which is the bad one.
  10. With the power off, open the control panel and visually inspect the branch circuits. Check branch fuses if the kiln has them.
  11. Locate the two wires that begin the bad branch circuit from the bunch that come from L1 and L2 on the main power block.
  12. Follow those wires to where they connect to the first component in line, probably either a fuse block, a relay or a switch.
  13. With the power ON, and any kiln-sitters or switches on High (so that the elements would come on if they could), take a voltage reading at the point where these two wires connect to the first component in line. The reading normally should be the same as what it is at the main power block. If it is not, one of the wires between the main power block and the first component is bad and needs to be replaced.
  14. If there is voltage there then take another reading after the first component at the point where the two wires continue onto the next component or to the element connection. If there is voltage after the component then the component is working.
  15. To determine whether the contactor or the switch is bad, first follow the wires from the load side of the switch to the contactor. 
  16. With the power all on and the switch on high, take a voltage reading where the two wires from the switch to the contactor connect to the contactor. If these readings are the same, then the contactor is bad.
  17. If there is no voltage present, then follow those two wires back up to the load side of the switch and measure the voltage there. If the voltage readings are the same, then the contactor is bad.
  18. If there is no voltage present, then follow those two wires back up to the load side of the switch and measure the voltage there. If the voltage reading is the same, then one of the wires is bad.
  19. If there is no voltage present at the load side of the switch (power all on, switch on high, then be sure voltage is coming to the switch; if it is, then the switch is bad. Replace the switch and if the problem still persists then repeat the test; you will most likely have to replace the contactor as well.
  20. If there is no voltage after the first component in line and it is not a relay/contactor, then just replace it. If it is a fuse holder, just replace the fuse (usually a bad fuse means there is a short somewhere in the circuit). Use a "continuity" tester to test for bad fuses. Always check tightness of connections in a questionable circuit.
  21. If there is voltage after the first component then move along the circuit from the main power block towards the element connections, testing for voltage before and after every component until you isolate the problem. Voltage readings taken from between the elements (and from between resistors in general) give a reading that reflects voltage which is half the supply voltage with two elements in series, and either one-third or two-thirds the supply voltage with three elements in series (depending on which side of the middle element in the series the test lead is placed).
  1. Check the tightness of all connections. Do this by wiggling the connector to make sure it is not loose.
  2. Examine all connections for any sign of oxidation or discoloration.
  3. Examine all wires for signs that the wire may have burned.
  4. Make sure all wires are connected to their proper connection point. You may have to compare the kiln to the wiring diagram to be sure of this. This step would be particularly important if a wire has come loose.
  5. Look for any place where a wire may have shorted against the metal case or a component.

CAUTION: Turn power off to kiln form the circuit breaker or unplug the kiln.

  1. On the next firing make up "cone packs" for each thermocouple.
  2. Once the cone packs are positioned on shelves and are visible through the peepholes, fire the kiln to the middle cone's number
  3. Start watching cones near the end of firing.
  4. Keep checking the control display to make sure it does not say CPLt.
  5. If the middle cones did not go down together then immediately note the differences in each thermocouple reading from the one thermocouple the same zone as the first cone that went down. Change the final set point of your program to reflect the difference.
  6. If the kiln is firing too hot then lower the final set point.
  7. If the kiln shut itself off before bending the cones properly, reprogram it and then restart it as quickly as possible. Record the temperature at which the kiln shut down. Stop and restart the kiln. Reprogram the same program to one cone number higher. Do these steps quickly. Watch the middle cones again and note at what temperature the cones properly bend. If they bent while you were programming then just offset the temperature by 5 or 6 degrees. Shut the kiln off once you note that temperature.
  1. Unplug kiln.
  2. Remove the control box and the insulation panel.
  3. Remove the wires to the relay.
  4. Remove the nuts from the studs that hold the relay in place. Remove old relay and replace with new one.
  5. Visually inspect the wire connectors. Do they look corroded or "cooked"? Are the wires frayed? Any corrosion on the wire itself? If any of this is questionable you should replace the appropriate wires.
  6. Reconnect all wires. Visually inspect to make sure the spade connectors are down as far as they can go and feel to see that they are tight (a gentle tug should not remove one). If they are loose for some reason remove the wire and slightly squeeze the spade connector with pliers to tighten it.

IMPORTANT: The slip on wire connectors cannot be loose or corroded. If there is a bad connection then heat will be generated and the component that they slip onto (relay, terminal strip, etc) may overheat and fail. If you squeeze the slip on terminal to make it tighter–be sure to squeeze it evenly so that one side is not tight and the other loose. If there are any doubts about the integrity of the wire or the connector replace the whole wire or harness.


How to check a relay in an Easy-Fire Kilns

  1. Similar in any L&L automatic kiln.
  2. Follow proper electrical safety practices.


  1. See this page for the 12 Volt 30 Amp relay we use for most kilns.
  2. See this page for the 240 Volt 30 Amp relay we use as a control relay for 480 volt kilns.
  3. See this page for all contactors and relays.


How to change a relay in an Easy-Fire Kilns

  1. Be sure to keep the wires on in the right sequence when changing a power or control relay in an Easy-Fire, Easy-Fire XT, School-Master or eQuad-Pro Kiln.
  2. The configuration is similar in a Jupiter panel or as control relay in a DaVinci, Hercules, or Easy-Load panel.
  3. Make sure kiln is unplugged or locked out and tagged out at the circuit breaker or fused disconnect switch when doing this maintenance.


  1. See this page for the 12 Volt 30 Amp relay we use for most kilns.
  2. See this page for the 240 Volt 30 Amp relay we use as a control relay for 480 volt kilns.
  3. See this page for all contactors and relays.


The most common cause of kiln slowdown, E-1 messages, and failure to reach temperature is element wear. As your elements age  they generally increase in electrical resistance. According to Ohm's Law, when resistance, measured in Ohms, increases, both Watts and Amperes will decrease, assuming Voltage remains constant. Since Amps and Watts are the measures of current and power respectively, they can be thought of as the amount of juice that your kiln has to generate heat. Obviously if you don't have enough power, your kiln will fire slowly and might not even reach the desired temperature.


Using resistance, we can tell exactly how much power your kiln has lost over the course of your element's life. For example on an e23T that uses 240V, a brand new kiln section would read about 14.5 ohms. If you measured this same kiln section after several months of cone 6 firings let's say and the reading was 16.5 Ohms, you would know that this section of elements has lost approximately 14% of it's power (16.5/14.5=1.138, or close to a 14% increase). Again, an increase in resistance means decrease in power. A very general rule of thumb is that most people will typically begin to notice some slowdown once you've lost more than 10% of your power. It will certainly vary based on the kiln you have, your voltage, as the types of firing you do. People only doing low fire work will continue to get by on lower power than those needing to go to higher temperatures (cone 6+). As you can see, measuring your element Ohms is the best way to identify when elements need replacing.

Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. How you figure out the section ohms depends on whether the elements are wired in Parallel or Series. Most kilns are wired in Parallel except for JD230V and most 18" kilns like the e18T. For a parallel kiln you take the per element ohms listed and divide by the number of elements per section. Ex. e23T 240V 1 Phase is 28.9 Ω per element with two elements per ring = 14.5 Ω per section.   Ex. 2. JD2927 240V is 36.5 Ω per element w/ three elements per ring = 12.2 Ω per section. See this link for more info on Series vs. Parallel

Here we will show how to best measure your element resistance for two groups of L&L Kilns, into which most models fall.


In these series' of kilns a piggy-backed control panel covers up the element terminals.

  1. Turn the power to the kiln completely OFF and unplug it if possible. If it is direct wired, then you should at least turn off all power at the disconnect switch or circuit breaker.
  2. Open the outermost control panel by unscrewing it either from the element cover box in the case of Easy-Fire, eQuad Pro, School Master and Liberty Belle kilns or from the kiln body in the case of Doll kilns.
  3. Once you open up that control panel you will see the element power wire terminal strip. See the picture. It will have numbered wires coming from the element terminal blocks and wires connecting to the power relays. There are two wires per kiln section/ring, so numbers 1 & 2 are for the top section, 3 & 4 for the middle, and 5 & 6 for the bottom section on a three ring kiln.
  4. Set your multimeter to Ohms (Omega symbol Ω) and using your testing leads, place one in between the two tabs/terminals w/ #1 wires connected. There is a small circular divot that the lead fits into (see picture). Put the other lead on terminal #2 and make note of the reading. Repeat the process for 3 & 4 and then for 5 & 6. Remember that each pair of wires represents one section.
  5. Compare your readings to those on the wiring diagram in your instruction manual. Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. See above for more info on understanding the readings.



In these series' of kilns, the control panel is separated from the kiln body and the element terminals are connected to the controls via external jumper cords or plugs.

  1. Turn the power to the kiln completely OFF and unplug it if possible. If it is direct wired, then you should at least turn off all power at the disconnect switch or circuit breaker.
  2. Unplug the first jumper cord from the control panel.
  3. Set your multimeter to Ohms (Omega symbol Ω) and using your testing leads, place one lead on each of the "hot" prongs. They will be the flat ones.
  4. Make note of the reading and move on to the next one.
  5. Compare your readings to those on the wiring diagram in your instruction manual. Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. See above for more info on understanding the readings.

See this tutorial on how to use a multimeter.

  1. Unplug kiln.
  2. Trace wiring for missing or bad connections.
  3. Check wiring against wiring diagram.
  4. Check for corroded connectors or connectors that have frayed wires. Replace any such connectors.