P255F

What it means

The A/C request input A is electrically intact, but its value does not match the system context — for example asserted while the HVAC controller reports off, toggling rapidly, or sustained while compressor pressures cannot support it. The ECM disables A/C clutch engagement until the input becomes plausible.

Is it safe to drive?

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

  high

  One of the most commonly reported causes for this code — check this first.

• Sensor element aged beyond calibration window

  low

  Less common, but worth ruling out after the more likely causes.

• Sensor mounting loose - signal damping

  low

  Less common, but worth ruling out after the more likely causes.

Related help

• Full P255F diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?