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.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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)
Common causes
Ordered by how often each turns out to be the cause.
- Heater element failedCommon
- Wiring open or connector loosePossible
Parts involved
- Reductant Tank Heater
- Reductant Heater Wiring
P20EB is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.