P2AFDEngine Coolant Temperature Sensor 4 Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2AFD flags a sensor 4 coolant reading that stays inside the electrical limits but makes no sense, for instance a value that disagrees with the engine's other temperature readings once everything has cooled down for hours, or that hardly moves while the engine warms up. CARB requires such rationality checks for coolant temperature inputs used by emission controls. No manufacturer documents the set condition of P2AFD publicly; NTN-SNR names it a deviation or malfunction of the sensor 4 signal. The sister codes for sensors 2 and 3 (P2183, P01E4) work the same way: makers compare the readings after hours of standstill or follow the warm-up curve. Typical causes are a drifting element, corrosion in the plug, an air pocket around the sensor tip or software that needs updating. Hard circuit faults belong to P2AFC, P2AFE and P2AFF.
- What you may notice
- Check engine light, often only after a cold start
- Sensor 4 value clearly differing from the others in live data
- Likely causes
- LikelyDrifting sensor element
- PossibleCorrosion adding resistance in the connector
- PossibleAir pocket at the sensor after coolant service
- RareControl software needing an update
- 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 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.