P255F code meaning
A/C Request A Circuit Range/Performance
What P255F means
P255F flags the A/C request A input as electrically sound but implausible: the request may switch on and off far more often than a real compressor demand would, stay set while the climate control is off, or disagree with what the engine module sees from the compressor side. The request lets the engine prepare for the compressor load by raising idle speed and torque reserve. CARB section (e)(12) requires monitoring of electronic A/C components when switching the A/C alters fuel or spark control, including failures that trigger the alternate strategy with the A/C off, phased in over 2006 to 2008. Saab's 2011 9-5 is an example of a design without such a wire, receiving the request as a bus message. No maker documents P255F publicly. P2519 is the general fault on input A, P256F the same check on input B.
P255F at a glance
- Check engine lightUsually not
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P255F
- Idle speed fluctuates when the A/C cycles
- A/C cooling intermittent or switched off
Common causes of P255F
- PossibleClimate control module sends erratic requests
- PossibleLoose contact on the request line causing chatter
- Less likelyRefrigerant pressure switch cycling abnormally
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ac request input aHvac module
What each part of P255F means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 5F | The exact fault in that area. |
What to do next
- Note P255F 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 P255F
What does P255F mean?
P255F means "A/C Request A Circuit Range/Performance". P255F flags the A/C request A input as electrically sound but implausible: the request may switch on and off far more often than a real compressor demand would, stay set while the climate control is off, or disagree with what the engine module sees from the compressor side. It is a generic code, so it means the same on every make.
Is it safe to drive with P255F?
P255F does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P255F fail an emissions test?
Yes, it can. P255F 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 P255F to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P255F 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.