P0ABB

What it means

P0ABB is a generic code meaning the hybrid or EV battery control unit has found the battery pack voltage sense 'A' circuit reading outside its expected range, or not agreeing with other voltage measurements. The control unit usually compares the pack voltage sensor with the sum of the individual cell or module voltages, or with other internal readings, and sets the code when they differ by too much or the signal looks implausible. The exact sensor location and the way the check is made depend on the make and model.

Symptoms

• Hybrid or EV system warning light, or malfunction indicator lamp, on
• Reduced power or the car going into a limited performance mode
• Hybrid system not starting, or the car refusing to go into Ready mode
• Inaccurate or fluctuating battery charge level display
• Charging that is slow, interrupted or will not start
• Engine running more than usual on a hybrid, with poor fuel economy

Possible causes

• Poor connection, corrosion or damage at the battery pack voltage sensor connector or wiringlikely
• Faulty pack voltage sensor or sensing circuit inside the battery control modulelikely
• Imbalance or a weak module in the battery pack causing a mismatch between pack and cell voltage readingspossible
• Loose or high-resistance high-voltage busbar or service disconnect connection affecting the voltage readingpossible
• Low 12 V auxiliary battery voltage or poor earth upsetting the control unit's measurementspossible
• Faulty battery control unit or outdated software calibration, where a known fault applies to that modelrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting pack voltage, current, temperature and state of charge when the fault set.
2. Check for other related codes, such as cell voltage, current sensor or insulation faults, as they point to the cause.
3. Test the 12 V auxiliary battery and charging, and check the main earth connections, as low voltage can cause false readings.
4. Inspect the battery pack sensor wiring and connectors for damage, corrosion, moisture or loose pins, following the manufacturer's high-voltage safety procedure.
5. Compare live pack voltage with the total of the individual cell or module voltages on a suitable scan tool to see which reading is wrong.
6. Check the battery pack for module imbalance or a weak module using the manufacturer's test procedure.
7. Check for any software updates or technical bulletins for the model that relate to this code.
8. Only if qualified and following high-voltage isolation procedures, inspect busbars and the service disconnect for tightness and heat damage.

How to fix

• Repair or replace damaged wiring and clean or replace faulty connectors in the sensing circuit.
• Replace the faulty voltage sensor or battery control module as the manufacturer's procedure directs.
• Rebalance or replace the affected battery module or pack if cell imbalance or a weak module is confirmed.
• Correct any loose high-voltage connections, using a qualified high-voltage technician.
• Replace or recharge the 12 V auxiliary battery and repair earth faults.
• Apply an official software update if one is known to cure the fault on that model.

Can I keep driving?

Nearby codes

• P0ABAGenericHybrid/EV Battery Pack Voltage Sense A Circuit
• P0ABCGenericHybrid/EV Battery Pack Voltage Sense A Circuit Low