Powertrain
generic / SAE
P256F
A/C Request B Circuit Range/Performance
A/C request input B is electrically intact but its value does not match the system context — same failure mode as the input A performance fault, applied to the second HVAC channel.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 6F
Possible causes
- HVAC module sending inconsistent request B high
- Sensor element aged beyond calibration window low
- Sensor mounting loose - signal damping low
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–500 €
- Estimated time: 0.4–2 h
- Component: ac request input b
- MIL / check engine light
Sources
References
sae:J2012