P2AFF code meaning
Engine Coolant Temperature Sensor 4 Circuit High
Powertrain system Generic code P2Axx codes Check engine light
What P2AFF means
P2AFF reports an excessive sensor 4 signal. For an NTC thermistor that means an implausibly cold reading, mostly from an open circuit, an unplugged connector or a line shorted to voltage. GM's 2019 tables for the 2.7 L L3B set P2AFF once the resistance rises above roughly 355 kΩ, equal to −60 °C, for 5 s in a 6 s window, with an engine run time above 10 s among the enabling conditions; Type B with MIL after two trips. Oddly, the same GM table names the radiator coolant sensor in the P2AFF row while assigning P2AFE to coolant sensor 4, but both channels share the same threshold. GM bulletin 21-NA-149 also lists P2AFF for chafed engine harnesses on its 1500 pickups. The engine computer then works with a substitute value. P2AFE is the short-to-ground case.
P2AFF 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 P2AFF
- Check engine light after two trips
- Implausibly cold coolant temperature in live data
- Thermal management running on a default value
Common causes of P2AFF
- Most likelyOpen signal wire or unplugged connector
- PossibleChafed engine harness
- PossibleSensor element open internally
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 P2AFF 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. |
| FF | The exact fault in that area. |
What to do next
- Note P2AFF 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 P2AFF
What does P2AFF mean?
P2AFF means "Engine Coolant Temperature Sensor 4 Circuit High". P2AFF reports an excessive sensor 4 signal. It is a generic code, so it means the same on every make.
Is it safe to drive with P2AFF?
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 P2AFF fail an emissions test?
Yes, it can. P2AFF 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 P2AFF 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 P2AFF clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.