What it means
Phase U current of the a/c compressor motor reports a current low condition. Phase commutation may be impaired.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The A/C compressor motor is driven by separate electrical phases, and the control module monitors current in phase U to manage motor commutation. This code sets when phase U current is lower than expected, which can result from a partly open phase winding or a current sensor that has drifted off its proper reading.
Common causes
Most likely first.
- Phase winding partially open
- Current sensor offset drifted
Symptoms
- Hybrid/EV system warning light on
- Air conditioning may be reduced or unavailable
How to diagnose it
- Record freeze-frame data and review related hybrid/EV and compressor codes to see when phase U current fell below expectation.
- Check scan-tool data for phase U current alongside the other phase readings during the manufacturer's prescribed operating test.
- Inspect the compressor electrical connector and accessible phase wiring for damage, corrosion, or a loose connection, observing high-voltage safety procedures.
- With the system isolated as directed by the manufacturer, test the phase U winding and wiring for an open or poor connection.
- If the phase winding and wiring pass, test the current sensor and compressor control module using the manufacturer's procedure.
Common fixes
- Repair a loose or damaged phase U connection or wiring fault.
- Repair the phase U winding connection if testing identifies a partial open.
- Replace the phase current sensor if its offset is outside the manufacturer's specification.
- Replace the compressor or control module only if testing confirms the fault is internal.
Can I keep driving?
Avoid using the A/C until this hybrid or EV compressor fault is diagnosed; the vehicle may limit or disable cooling and may show a system warning. Do not handle compressor high-voltage wiring, and follow the vehicle's warning instructions.
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.