What it means
The current sensor for drive motor A phase U reports a circuit low fault. Phase current measurement is unreliable.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Drive motor A phase U carries one of the motor’s controlled currents, and its current sensor feeds that measurement to the inverter control system. The ECM monitors the sensor circuit and sets this code when the phase U signal is lower than its usable range. The module then cannot use the current measurement reliably to control motor output.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced motor power or torque
- Possible limp mode or vehicle shutdown
How to diagnose it
- Save freeze-frame data and check for related inverter or phase current codes to establish whether the low signal is specific to drive motor A phase U.
- Compare live phase U current data with phases V and W for a signal that is fixed low or inconsistent with the operating state.
- With the vehicle safely powered down, inspect accessible phase U sensor wiring and connector terminals for corrosion, damage, or a signal conductor shorting to ground.
- Have a qualified technician test the phase U signal circuit for a short to ground and check terminal contact using manufacturer wiring information.
- If the harness and connector pass, test the phase U current sensor for an internal short against the manufacturer’s specification.
Common fixes
- Clean and secure corroded or loose phase U sensor connector terminals.
- Repair damaged phase U wiring that is shorted to ground.
- Replace the phase U current sensor if testing confirms an internal short.
- Clear the code and verify plausible phase U current data after repair.
Can I keep driving?
Avoid high-load driving because inaccurate phase U feedback can make the inverter limit motor power or enter limp mode. If the vehicle warns of shutdown or loses substantial power, stop safely and arrange recovery.
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.