P2C39 code meaning
Cylinder Head Temperature Sensor B Range/Performance
Powertrain system Generic code P2Cxx codes Check engine light
What P2C39 means
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.
P2C39 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.3 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P2C39
- 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
Common causes of P2C39
- Most likelyPCM calibration misjudging sensor B (Ford EcoBoost bulletins, cured by reprogramming)
- PossibleSensor B drifted or responding slowly
- Less likelySensor not seated properly in the head or corroded terminals
- Less likelyGenuine local overheating from low coolant or trapped air
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cylinder head temperature sensor bWiring harnessECM
What each part of P2C39 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| C | Area: hybrid propulsion. |
| 39 | The exact fault in that area. |
What to do next
- Note P2C39 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2C39
What does P2C39 mean?
P2C39 means "Cylinder Head Temperature Sensor B Range/Performance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P2C39?
Drive gently and only to a workshop. With P2C39 the car can go into limp mode (reduced power) to protect itself.
Will P2C39 fail an emissions test?
Yes, it can. P2C39 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2C39 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2 hours of work. This is a job for a workshop.
Will P2C39 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.