BENTRUP ERROR CODES - EXPLAINED
Has your kiln stopped mid firing? Are you getting error codes on your controller that you dont understand? Here is a complete run through of the most common error codes, what they mean and how to fix them.
Thermocouple & Temperature Reading Codes
EA1 — Temperature Reading Fault
⚠️ This is a common fault for reding the temperature in your kiln and relaying that reading to your controller. But EA1 is the fault code but it will have another code as well that describes what has happened.
EA1 always appears with a "second code" i.e. our, udr, inu:
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EA1 + our → thermocouple broken
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EA1 + udr → polarity reversed or wrong type
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EA1 + inu → internal electronics fault
So, what do the "Second Codes" mean?
"Second Codes" Explained:
“our” = Thermocouple overrun
⚠️ The kiln cannot read the thermocouple and assumes extreme temperature.
Causes:
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Broken thermocouple
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Loose or dirty connections
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Wire snapped or unplugged
Fix: Check the thermocouple is plugged in properly and not damaged.
“udr” = Thermocouple underrun
⚠️ The kiln thinks it is below 0°C. Reversed polarity causes udr or EA1 + udr.
Causes:
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Thermocouple wires reversed
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Wrong thermocouple type
Thermocouple Polarity
🔧 Correct polarity is essential.
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Red strip on ceramic block = Positive (+)
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Orange Bentrup cable = Positive (+)
Fix: Check Thermocouple (TC) polarity and (TC) type.
“inu” — Cold‑Junction Fault
❌ Internal temperature‑reading electronics have failed.
Fix: Email Cobcraft. This requires a controller repair or replacement.
Heating & Firing Performance Codes
EA3 — Over‑Temperature Shutdown
🔥 The kiln exceeded the programmed temperature by more than 20°C.
Fix: Let the kiln cool, Email Cobcraft — this may indicate a stuck contactor.
EA4 — Heating Too Slowly
🐢 EA4 means the kiln cannot keep up with the programmed ramp rate.
Example: If set to 100°C/hr and the kiln heats at 99°C/hr or less, EA4 appears.
Causes of EA4
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Thermocouple is not in the kiln 🎯 If it is outside the chamber, the kiln sees no temperature rise.
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Cold room or poor insulation 🌬️ Drafts, wind, open sheds, cold studios, the kiln is too close to cold or wet walls, gaps in the fibre around the base, enlarged vent holes or missing fibre.
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Aged elements 🧓 Old elements have higher resistance and produce less power. An 8 kW kiln may behave like a 6 kW kiln.
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Broken or melted element wires 🔥 Burnt tails, melted wires, loose or rusty terminals, or shorted (burnt) wiring.
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Missing phase (3‑phase kilns) ⚡ A missing phase reduces power dramatically. Customer‑safe check: look for a tripped breaker on your house fuse box.
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Failed or weak contactor 🧲 A burnt or stuck contactor reduces power.
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Simmerstats not on HI (if fitted) 🔄 If off or too low, the kiln is de‑powered.
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Lid safety switch not engaging 🛑 If the lid switch does not click, the kiln will not get any power to the elements as it assumes the lid is open - Safety Feature.
What You Can Try Before Emailing Cobcraft
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Lower the ramp rate by about 20%. 🧪 This gives the kiln more time to heat.
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Use SKIP mode. ⏩ This tells the kiln to heat as fast as it can.
How to access SKIP:
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Go to the ramp rate
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Increase to 999
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Press UP once more
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Display shows “SKIP”
Useful for kilns with aged elements that still work but cannot meet strict ramp rates.
Email Cobcraft if:
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You have checked the simple items
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You have tried lowering the ramp rate or SKIP
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EA4 still appears
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You suspect wiring, elements, or contactor issues
📧 Email keeps all support logged in our CRM system (Tradify).
EA8 — Ramp Not Achieved
ℹ️ The kiln could not reach the programmed rate, even after extra soak time. Firing continues to try and reach temperature, if it fails for too long an EA4 error code will activate and power down the elements.
EA9 — Uncontrolled Ramp Completed
ℹ️ The kiln skipped a segment because it could not reach the target temperature. Firing continues to try and reach temperature, if it fails for too long an EA4 error code will activate and power down the elements.
Power‑Related Codes
E62 — Power Cut (Firing Continued)
🔌 Power returned quickly. Firing will continue to finish the program.
E63 — Power Cut (Firing Stopped)
🔌 Power was out too long. The kiln is now reset to the end of the program, you may need to restart the firing.
E64 — Room Too Hot
🌡️ The controller shut the kiln down because the studio temperature is too high. Improve airflow or ventilation - very uncommon fault.
Internal Controller Codes
EC… — Internal Controller Fault
❌ Electronics issue. Email Cobcraft.
Ed… — Internal Controller Fault
❌ CPU, memory, or configuration issue. Email Cobcraft.
Additional Behaviour Notes
What Happens After a Power Cut
🔄 The kiln decides whether to continue or stop.
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If power comes back quickly the kiln continues firing by itself.
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If the kiln cools more than 50°C The firing stops to protect your work.
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If the kiln was already warm the controller shortens the ramp time and starts again from the current temperature.
If the kiln cannot keep up with the ramp
🟠 The kiln pauses and waits for temperature to catch up.
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The kiln pauses
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The Start/Stop light turns orange
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It waits until the temperature catches up
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Then continues
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If this happens often, the firing will still finish but will take longer than programmed.