What it means
Phase U current of the a/c compressor motor reports a current high 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 uses multiple electrical phases, and the control module monitors phase U current to control motor commutation. This code sets when phase U current is higher than expected, which can indicate a short between motor phases or a stalled rotor drawing excessive current.
Common causes
Most likely first.
- Short between motor phases
- Rotor stalled - high stall current
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 compressor and hybrid/EV codes to see whether the high phase U current occurred during startup or while the compressor was running.
- Check scan-tool data for phase U current and compare it with the other phase readings during the manufacturer's prescribed test.
- Inspect the compressor connector and accessible phase wiring for damage, contamination, or signs of a short, following high-voltage safety procedures.
- With the system isolated as directed by the manufacturer, test the motor phase wiring and winding for a short between phases.
- If the wiring tests correctly, use the manufacturer's procedure to assess whether the compressor rotor is stalled and whether the current sensor is reporting accurately.
Common fixes
- Repair damaged phase wiring or a connector causing a short between phases.
- Correct a verified high-resistance mechanical obstruction or compressor condition only as specified by the manufacturer.
- Replace the compressor if its motor windings are shorted or the rotor is confirmed stalled.
- Replace the phase current sensor or control module only if testing confirms inaccurate current measurement or control.
Can I keep driving?
Do not keep commanding the A/C compressor while phase U current is high; excessive current can worsen compressor or power electronics damage. Follow any hybrid or EV warning and avoid handling high-voltage components.
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.