Powertrain
generic / SAE
P20B1
Reductant Heater Coolant Control Valve Circuit/Open
The drive circuit for the engine-coolant control valve that warms the DEF tank/lines is open — coolant cannot be routed to the heating loop.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / B1
Possible causes
- Solenoid winding open high
- Pin pushed back out of connector body low
- Cracked solder joint inside the module or sensor low
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)
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 100–700 €
- Estimated time: 0.7–2.5 h
- Component: reductant coolant valve
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012