P2C38Cylinder Head Temperature Sensor B Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- A cylinder head temperature sensor is an NTC thermistor seated in the head metal that tells the module how hot the engine really is, even without coolant. P2C38 is the general circuit fault of a second such sensor, B: the signal is open, shorted or otherwise unusable, without separating low from high (P2C3A/P2C3B do that, P2C39 judges plausibility). Ford uses it on the 2025 Explorer and Aviator with 2.3 L or 3.0 L EcoBoost: TSB 24-2393 (built until 15 Oct 2024) describes an over-temperature warning with P1299 plus P2C38 or P2C39 although fan and coolant are fine, and cures it by reprogramming the PCM. For sensor A Ford's 2024 summary flags below 0.244 V or above 4.96 V after 5 s. CARB treats head temperature sensors used for emission control like coolant sensors.
- What you may notice
- MIL and engine over-temperature warning
- Fail-safe cooling mode with reduced power possible
- Temperature warning even though coolant level and fan are fine
- Likely causes
- LikelyPCM software causing false faults (Ford 2025 Explorer/Aviator, TSB 24-2393)
- PossibleLoose or corroded connector at the head sensor
- PossibleFailed head temperature sensor B
- RareHeat-damaged or chafed wiring near the cylinder head
- 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 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.