What it means
Generator phase U current is above the expected range. The code identifies a high-current condition but does not establish its cause.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The inverter and hybrid control system monitor current in generator phase U while controlling generator output. This code sets when phase U current is higher than expected, potentially because of a phase short or a stalled generator rotor creating excessive current.
Common causes
Most likely first.
- Short between motor phases
- Rotor stalled - high stall current
Symptoms
- Check-engine or hybrid-system warning light
- Reduced hybrid performance
- Possible reduced-power mode
How to diagnose it
- Record freeze-frame data and compare live generator phase U current with phases V and W to establish whether the high reading is persistent or occurs only under load.
- Check for related generator, inverter, or motor-stall codes and note any loss of hybrid power or abnormal operating conditions.
- With high-voltage safety procedures followed, inspect generator phase U wiring and inverter and generator connectors for shorts, damaged insulation, or overheating.
- Have a qualified technician test phase-to-phase and phase-to-ground insulation and generator winding condition against the manufacturer's specification.
- If the wiring and winding checks pass, assess generator rotation or mechanical binding and compare inverter current-sensor readings across all three phases.
Common fixes
- Repair damaged or shorted phase U wiring and connector terminals.
- Repair or replace a generator winding confirmed shorted to another phase or ground.
- Address a confirmed mechanical cause of a stalled generator rotor.
- Repair the inverter current-sensing or switching circuit if testing identifies it as the source.
Can I keep driving?
Do not continue driving if power drops, the vehicle stalls, or a hybrid warning tells you to stop; high phase current can lead to reduced-power mode or shutdown. Keep clear of high-voltage parts and arrange prompt diagnosis.
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.