OBD Engine Coolant Heater A Control Circuit Driver Current/Temperature Too High
What it means
P01F8 stands for Engine Coolant Heater A Control Circuit Driver Current/Temperature Too High. P01F8 is a P code, so the fault sits in the engine, transmission and emissions systems. For P01F8, the second digit places it in fuel and air metering. For P01F8, work through the cause list below, cheapest checks first.
What to check first
For P01F8, pull the connector and inspect the terminals for spread, corrosion or backed-out pins before testing anything else.
Check these first
- P01F8: Faulty or contaminated sensor in the fuel/air metering circuit
- P01F8: Damaged or shorted wiring or connector for the affected circuit
- P01F8: Vacuum leak or intake system restriction
- P01F8: Failing fuel pump, injector, or fuel pressure regulator
What to do next
P01F8 is a fault in the fuel and air metering system. The steps below are general, so what actually failed on your vehicle may not be what P01F8 names.
- P01F8: Read freeze frame data and related codes with an OBD-II scanner
- P01F8: Inspect the affected sensor wiring and connector for damage
- P01F8: Compare live sensor readings (fuel trim, airflow, temperatures) to manufacturer specs
- P01F8: Smoke test the intake system if lean or vacuum conditions are suspected
- P01F8: Replace the failed component after confirming it with live data
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.