OBD-II code · Powertrain (generic)
P01E9 Engine Coolant Heater A Control Circuit Low
Engine Coolant Heater A Control Circuit Low: the control-circuit voltage is below the expected range. Often a short to ground or high resistance in the wiring.
Is it safe to drive with P01E9?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyWiring shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- Parts involved
- Coolant Heater A, Heater Wiring
Related codes
- P01EDEngine Coolant Heater B Control Circuit Low
- P01E6Engine Coolant Temperature Sensor 3 Circuit High
- P01E7Engine Coolant Temperature Sensor 3 Circuit Intermittent/Erratic
- P01E8Engine Coolant Heater A Control Circuit/Open
- P01EAEngine Coolant Heater A Control Circuit High
- P01EBEngine Coolant Heater A Control Circuit Performance
- P01ECEngine Coolant Heater B Control Circuit/Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.