OBD-II code · Powertrain (generic, extended)
P2B79 Coolant Heater B Control Circuit Performance
The control circuit of coolant heater B reports a control circuit performance condition. Auxiliary preheating of the coolant cannot be commanded as expected.
Is it safe to drive with P2B79?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHeater element aged - low output
- PossibleSupply voltage low under load
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Usually unaffected
- Parts involved
- Coolant Heater B, Wiring Harness, Ecm
Related codes
- P2B75Coolant Heater A Control Circuit Performance
- P2B76Coolant Heater B Control Circuit/Open
- P2B77Coolant Heater B Control Circuit Low
- P2B78Coolant Heater B Control Circuit High
- P2B7AEVAP System Pressure Sensor/Switch C Circuit
- P2B7BEVAP System Pressure Sensor/Switch C Circuit Range/Performance
- P2B7CEVAP System Pressure Sensor/Switch C Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.