Powertrain
generic / SAE
P2CF2
Auxiliary Thermostat B Stuck Closed
The auxiliary thermostat B is stuck closed. Coolant cannot flow through the affected branch, risking overheating in the bypassed path.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberC / F2
Possible causes
- Thermostat element failed high
- Wax pellet aged - element non-responsive medium
- Carbon or debris buildup preventing free movement low
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 60–400 €
- Estimated time: 0.5–3 h
- Component: aux thermostat b
- Component: engine coolant loop
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012