P2AFE code meaning
Engine Coolant Temperature Sensor 4 Circuit Low
Powertrain system Generic code P2Axx codes Check engine light
What P2AFE means
Coolant sensors are NTC thermistors, so a signal from sensor 4 that is too low stands for an impossibly hot reading, usually a signal wire grounded or a shorted element. GM documents P2AFE for the 2.7 L turbo four (L3B) in its 2019 tables: the configurable temperature input system sets it when the resistance of the sensor 4 channel drops below about 41 Ω, corresponding to 150 °C, for 5 s within a 6 s window; Type B, so the MIL follows on the second trip. In bulletin 21-NA-149 GM names P2AFE as one consequence of engine harness chafing on 2019 to 2021 Silverado and Sierra 1500 trucks, the 2.7 L included. Because a hot reading is first taken at face value, the fans may run at full speed. P2AFF is the opposite fault, P2AFD the plausibility check.
P2AFE at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2AFE
- Check engine light after two trips
- Cooling fans running at full speed
- Implausibly high coolant temperature in live data
Common causes of P2AFE
- Most likelySignal wire shorted to ground, for example by harness chafing
- PossibleInternally shorted sensor
- Less likelyFaulty input in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine coolant temperature sensor 4Wiring harnessECM
What each part of P2AFE means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| A | Area: hybrid propulsion. |
| FE | The exact fault in that area. |
What to do next
- Note P2AFE 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 P2AFE
What does P2AFE mean?
P2AFE means "Engine Coolant Temperature Sensor 4 Circuit Low". Coolant sensors are NTC thermistors, so a signal from sensor 4 that is too low stands for an impossibly hot reading, usually a signal wire grounded or a shorted element. It is a generic code, so it means the same on every make.
Is it safe to drive with P2AFE?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2AFE fail an emissions test?
Yes, it can. P2AFE 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 P2AFE to fix?
Difficulty: easy. A typical repair takes 0.3 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2AFE clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.