P2C39Cylinder Head Temperature Sensor B Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2C39 flags a second cylinder head temperature sensor, B, whose voltage is electrically valid but whose reading does not fit the engine's state, for instance a value that jumps, lags or disagrees with other temperature inputs. Ford is the documented user, all on EcoBoost engines: TSB 24-2441 and its successor 26-2217 (F-150 2.7 L, 2024–2025) pair it with P1299 or P1285 and an over-temperature warning while fan and coolant are fine; a 2024 truck with P2C39 gets new PCM software, the CHT sensor is renewed only if P1285/P1299 persist. TSB 24-2393 (2025 Explorer/Aviator 2.3/3.0 L built to 15 Oct 2024) and 25-2206 (Bronco/Ranger 2.7 L built to 17 Mar 2025) also cure it by reprogramming. Out-of-range voltages are P2C3A/P2C3B.
- What you may notice
- Engine over-temperature warning although the gauge and coolant level look normal
- Check engine light, often together with P1299 or P1285
- Reduced power while the fail-safe cooling strategy is active
- Likely causes
- LikelyPCM calibration misjudging sensor B (Ford EcoBoost bulletins, cured by reprogramming)
- PossibleSensor B drifted or responding slowly
- RareSensor not seated properly in the head or corroded terminals
- RareGenuine local overheating from low coolant or trapped air
- 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: €50 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.