Code result
P256F
A/C Request B Circuit Range/Performance
Moderate severity
What it means
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.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
HVAC module sending inconsistent request B
highOne of the most commonly reported causes for this code — check this first.
Sensor element aged beyond calibration window
lowLess common, but worth ruling out after the more likely causes.
Sensor mounting loose - signal damping
lowLess common, but worth ruling out after the more likely causes.
Related help
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