What it means
The ECM detects a performance fault on the a/c compressor motor voltage sensor a. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Voltage sensor A provides feedback about the electric A/C compressor motor voltage for compressor control. This code sets when the signal is present but its behavior does not match the expected range or response, so the module cannot use it reliably.
Common causes
Most likely first.
- Sensor characteristic drifted
- High-resistance contact
Symptoms
- A/C warning light may come on
- Air conditioning may provide little or no cooling
- A/C operation may be limited or disabled
How to diagnose it
- Save freeze-frame data and monitor sensor A voltage live while the compressor is commanded on and off to identify when the reading becomes implausible.
- Inspect sensor A’s connector and wiring for loose or oxidized terminals, damaged insulation, or poor pin contact.
- Check the sensor circuit’s power, ground, and signal paths for excessive resistance or voltage drop using the wiring diagram.
- Compare sensor A’s output as operating conditions change with the manufacturer’s specification to distinguish drift from a connection problem.
- If the circuit checks out, test sensor A and the compressor control system using the manufacturer’s diagnostic procedure.
Common fixes
- Clean and secure sensor A connector terminals with an approved repair method.
- Repair high-resistance wiring or terminal connections in the sensor circuit.
- Replace sensor A if its output drifts outside the specified performance range.
- Repair or replace a compressor control component only if testing identifies it as the cause.
Can I keep driving?
A/C cooling may be limited or disabled while the module rejects sensor A’s unreliable response. You can generally drive if there are no other vehicle warnings, but arrange diagnosis soon and do not depend on A/C for clearing fogged windows.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.