P2C3DCylinder Head Temperature Sensor A/B Correlation
- 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
- An engine with two head temperature sensors can check one against the other: after a long soak both should read close to each other and to coolant temperature, and while running their gap should stay inside an expected band. P2C3D means sensors A and B disagree beyond that limit although neither circuit shows a fault. No manufacturer publicly documents the code or its thresholds. From 2019, phased in until 2021, CARB asks makers that use extra component temperature sensors, also where those sensors sit in different coolant circuits, to have a monitoring plan approved. Ford's 2.7 L EcoBoost bulletins show that both PCM software and a revised CHT sensor can be to blame for implausible head readings. Compare both values on a cold engine; the one far from coolant temperature is suspect.
- What you may notice
- Check engine light without driveability complaints
- Clearly different values for head temperature A and B after a cold start
- Likely causes
- LikelyOne of the two sensors has drifted out of tolerance
- PossibleContact resistance in one sensor circuit shifting its reading
- RareEngine control software judging the pair too tightly
- RareReal temperature difference from air pocket or poor flow in one head area
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.