What it means
The ECM detects a low fault on the a/c compressor motor voltage sensor a circuit. 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 feeds the electric A/C compressor motor voltage signal to the control module. This code sets when that signal falls below the expected range, pointing to a short to ground, an internally shorted sensor, or a poor connector contact.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
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
- Record freeze-frame data and watch sensor A voltage live to verify the low reading and its relationship to compressor operation.
- Inspect the sensor A connector and harness for chafing against ground, corrosion, loose terminals, or damaged insulation.
- Use the wiring diagram to check whether the signal wire is shorted to ground and confirm the sensor’s power and ground circuits.
- With the circuit safely isolated per service information, check wiring continuity and connector resistance for an unintended ground or poor contact.
- If the wiring checks out, test voltage sensor A against the manufacturer’s specification for an internal short or failed output.
Common fixes
- Repair a signal wire shorted to ground.
- Clean or replace corroded, loose, or damaged connector terminals.
- Repair damaged sensor wiring or restore its power feed.
- Replace voltage sensor A if it fails the specified circuit test.
Can I keep driving?
The A/C compressor may be limited or disabled, causing weak or no cooling. Driving is usually possible if there are no other warnings, but fix the circuit promptly and do not count on A/C to demist the windshield.
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.