What it means
A/C Compressor Motor Phase W Current Sensor Circuit Low: the signal voltage is below the expected range. Often a short to ground or high resistance in the wiring.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The phase W current sensor measures current in one electrical phase of the A/C compressor motor. This code sets when the sensor circuit signal is lower than the control module expects, which can result from a short to ground, excessive resistance, or a failed sensor.
Common causes
Most likely first.
- Current sensor failed
- Wiring fault
- Connector pins corroded - high contact resistance
Symptoms
- A/C warning light or check-engine light
- Air conditioning may cool poorly or stop cooling
How to diagnose it
- Capture freeze-frame data and check the phase W sensor reading on a scan tool to confirm the low signal occurs when the fault is present.
- Inspect the phase W sensor connector and harness for chafing to ground, corrosion, loose pins, or water intrusion.
- Check the phase W signal wire for a short to ground and inspect connector terminals for high resistance using the manufacturer's wiring information.
- Test circuit continuity and sensor supply and ground as specified by the manufacturer.
- If the wiring and terminals pass, test the phase W current sensor against the manufacturer's specification.
Common fixes
- Reconnect the phase W sensor connector and correct loose terminal fit.
- Repair wiring shorted to ground or damaged by chafing.
- Clean or repair corroded terminals that add resistance.
- Replace the phase W current sensor if it fails testing.
Can I keep driving?
The compressor may stop cooling because its phase W current signal is too low for reliable control. Driving is generally possible if no other warnings appear, but heed any hybrid or EV system alert.
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.