What Do My Eberspacher Error Codes Mean?
Here’s a practical, installer-friendly table of common Eberspächer diesel heater error codes, what they usually mean, and what typically causes them.
(Exact wording can vary slightly by model and controller, but these are the faults we see most often in the real world.)
Common Eberspächer Error Codes & Causes
|
Error Code |
Description |
Most Common Causes |
|
000 / No code |
Heater not responding |
No power, blown fuse, wiring issue, flat battery |
|
11 |
Undervoltage |
Low battery, voltage drop during startup, undersized wiring |
|
12 |
Overvoltage |
Charging system fault, incorrect power supply |
|
13 |
Overheating |
Blocked air ducts, restricted exhaust, poor airflow, dust buildup |
|
14 |
Temperature sensor fault |
Faulty sensor, wiring issue, internal sensor failure |
|
17 |
Flame-out |
Air in fuel line, low fuel level, fuel pump not delivering |
|
20 |
No start |
Fuel not reaching heater, unprimed line, blocked fuel line |
|
21 |
Repeated failed starts (lockout) |
Tried starting too many times with air in fuel line or low voltage |
|
30 |
Combustion air fan fault |
Fan jammed, wiring issue, internal motor failure |
|
31 |
Fan speed out of range |
Carbon buildup, failing fan motor, control issue |
|
33 |
Glow plug fault |
Failed glow pin, poor connection, age/wear |
|
34 |
Glow plug interruption |
Wiring fault, control unit issue |
|
47 |
Fuel pump interruption |
Pump wiring fault, incorrect pump angle, failed pump |
|
52 |
Control unit fault |
Internal ECU issue, moisture ingress, voltage spikes |
|
90 |
Heater locked out |
Multiple serious or repeated faults logged |
A Few Important Notes
- Lockout errors (like 021 or 090) will not clear by cycling power or pulling fuses — diagnostics are required.
- Undervoltage (011) is one of the most common faults and often blamed on the heater when the real issue is wiring or battery condition.
- Failed start errors almost always trace back to fuel delivery, not a “bad heater.”
- Error codes may display differently depending on whether you’re using EasyStart, DigiMax, or older controllers, but the fault itself is the same.
Pro Tip (From the Field)
If you see a failed start error:
👉 Do not keep retrying.
Fix the fuel or power issue first, then clear the code. Repeated attempts are the fastest way to force a lockout!