P2AFCEngine Coolant Temperature Sensor 4 Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2AFC is the general circuit code for a fourth engine coolant temperature sensor. Engines with split cooling, electric pumps or separate head, block, radiator and heater circuits carry several such sensors, and how they are numbered is up to each maker. No manufacturer documents a set condition for P2AFC publicly; for the 2019 L3B 2.7-litre engine GM instead assigns separate low and high codes to this sensor (P2AFE, P2AFF). Supplier NTN-SNR describes P2AFC in its coolant sensor catalogue as an electrical defect in the circuit of sensor 4. CARB requires coolant temperature inputs to be monitored for broken circuits and for values outside their range. Expect an open line, a loose plug or a failed NTC element; the engine computer then falls back on a substitute value.
- What you may notice
- Check engine light on
- Cooling fans running more than usual on substitute value
- Thermal management in default mode
- Likely causes
- LikelyOpen wire or loose connector at sensor 4
- PossibleFailed NTC element in sensor 4
- RareFaulty input stage in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €30 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.