OBD-II code · Powertrain (generic, extended)
P20EB Reductant Reservoir Heater "A" Control Circuit
A general electrical fault on the reductant tank heater "A" control circuit. AdBlue freezes at -11 C, so the tank heater must work for cold-start dosing.
Is it safe to drive with P20EB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHeater element failed
- PossibleWiring open or connector loose
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Reductant Tank Heater, Reductant Heater Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.