P0A58

What it means

P0A58 means the hybrid or electric vehicle's motor control system has seen the signal from the drive motor 'B' current sensor sit higher than its valid range. The control unit compares this reading with the expected current for the torque requested and with other sensors. A signal stuck high usually points to a circuit fault or a faulty sensor, though a real over-current condition cannot be ruled out. Which motor is 'B' and where the sensor sits depends on the model.

Symptoms

• Hybrid or powertrain warning light on
• Reduced power or the car going into limp mode
• Electric drive assist unavailable, or the engine running more than normal on a hybrid
• Car refusing to enter ready mode or shutting down while driving
• Rough, jerky or inconsistent motor response under acceleration
• Reduced efficiency or higher fuel consumption on a hybrid

Possible causes

• Faulty drive motor B current sensor, which is often built into the inverter assemblylikely
• Wiring fault in the sensor circuit, such as a short to voltage or a chafed or damaged harnesslikely
• Corroded, loose or contaminated connector at the sensor or inverterpossible
• Fault in the sensor's reference or supply voltage, or a poor groundpossible
• Internal fault in the inverter or motor control modulepossible
• Weak or faulty 12 volt battery or charging system causing unstable low-voltage supplyrare
• Genuine over-current from a motor winding or inverter power stage faultrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data. Note any other motor, inverter, resolver or high-voltage codes, and the conditions when the fault set.
2. Check the 12 volt battery condition and charging voltage, as low-voltage problems can cause false sensor faults and multiple codes.
3. Check for technical service bulletins and known issues for this model and software level.
4. With the high-voltage system made safe by a suitably trained person following the manufacturer's procedure, inspect the sensor and inverter wiring and connectors for damage, water ingress, corrosion and bent or pushed-back pins.
5. Look at live data for motor B current at rest and at zero torque. A reading stuck high or well off zero with no load suggests a sensor or circuit fault.
6. Test the sensor's supply, ground and signal circuits for short to voltage, open circuit and high resistance, using the wiring diagram for the model.
7. Compare the sensor reading with the other motor current values and the requested torque to see whether it is a real or false reading.
8. If the wiring and supplies are good, have a qualified technician check the motor and inverter insulation and phase condition before condemning the inverter.

How to fix

• Repair or replace damaged wiring and clean or replace faulty connectors and terminals in the sensor circuit.
• Replace the drive motor B current sensor if the manufacturer lists it as serviceable on its own.
• Replace or repair the inverter assembly if the sensor is integral or the internal electronics are faulty.
• Restore a healthy 12 volt supply by replacing the battery or repairing the charging fault if it is the cause.
• Repair or replace the motor or inverter power components if a genuine over-current fault is confirmed.
• Update the control unit software only if the manufacturer lists an outdated calibration as a known cause for this fault.

Can I keep driving?

Nearby codes

• P0A57GenericDrive Motor B Current Sensor Circuit Low
• P0A59GenericGenerator Current Sensor Circuit