P0BBB

What it means

P0BBB is the generic code for a Hybrid/EV Battery Voltage Sense 'Z' Circuit High fault. The hybrid or battery control unit measured a signal on that voltage sense circuit above the expected range, which points to an electrical fault in the circuit, the sensor or monitoring electronics, or a genuine over-voltage reading. Which part of the pack or circuit 'Z' refers to depends on the manufacturer and model, so check the vehicle-specific data.

Symptoms

• Hybrid or EV system warning light on the dashboard
• Reduced power or limp mode
• Hybrid system not engaging, or the engine running more than usual on a hybrid
• Reduced electric range or odd state-of-charge readings
• Car will not go into Ready mode or will not charge

Possible causes

• Wiring fault on the voltage sense circuit, such as a short to voltage, chafing or a damaged harnesslikely
• Corroded, loose or damaged connector pins at the battery monitoring module or the pack connectorlikely
• Faulty battery voltage sensing or monitoring module giving a false high readingpossible
• Genuine cell or module voltage imbalance or over-voltage within the battery packpossible
• Faulty hybrid or battery control unitrare
• Outdated control unit software where the manufacturer has published a fix for this faultrare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting any other battery, isolation or communication codes.
2. Check for manufacturer service bulletins and software updates for this code on the specific model.
3. Look at the live data for the pack and individual sense voltages, and see whether the 'Z' reading is out of line with the others or with the total pack voltage.
4. Only if trained and qualified for high-voltage work, isolate the high-voltage system using the manufacturer's procedure, then inspect the low-voltage sense wiring and connectors for damage, moisture, corrosion and pin tension.
5. Check the sense circuit for continuity, short to voltage and short to earth, and check the reference supply and earth to the monitoring module, using the wiring diagram.
6. Have a qualified technician measure the actual pack and module voltages and compare them with the scan data to decide between a real battery issue and a sensing fault.
7. Clear the code and road test, then recheck live data to see if the fault returns and under what conditions.

How to fix

• Repair or replace damaged wiring on the sense circuit and secure the harness away from chafing points.
• Clean or replace corroded or damaged connectors and terminals.
• Replace the faulty battery monitoring or voltage sensing module if the readings are proven false.
• Have a qualified technician rebalance, repair or replace the affected battery module if a genuine voltage problem is found.
• Update the control unit software if an update is available for this fault, or replace the control unit if it is proven faulty.

Can I keep driving?

Nearby codes

• P0BBAGenericHybrid/EV Battery Voltage Sense Z Circuit Low
• P0BBCGenericHybrid/EV Battery Voltage Sense Z Circuit Intermittent/Erratic