P255FA/C Request A Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Idle speed fluctuates when the A/C cycles
- A/C cooling intermittent or switched off
- Likely causes
- PossibleClimate control module sends erratic requests
- PossibleLoose contact on the request line causing chatter
- RareRefrigerant pressure switch cycling abnormally
- Inspection (ITP)
- Can matter for the ITP: it concerns the emissions system.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €40 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.