OBD-II code · Powertrain (generic, extended)
P20C0 Reductant Heater B Control Circuit High
Reductant heater B control line stuck high — short to B+. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P20C0?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyShort to B+
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
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
- 0.7–3 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Line Heater B
Related codes
- P20BCReductant Heater A Control Circuit High
- P20BDReductant Heater B Control Circuit/Open
- P20C4Reductant Heater C Control Circuit High
- P20C8Reductant Heater D Control Circuit High
- P20BEReductant Heater B Control Circuit Performance
- P20BFReductant Heater B Control Circuit Low
- P20C1Reductant Heater C Control Circuit/Open
- P20C2Reductant Heater C Control Circuit Performance
- P20C3Reductant Heater C Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.