P0B92

What it means

P0B92 means the hybrid or EV battery control unit has seen a voltage signal that is too low on the circuit for battery voltage sense 'R'. The signal is below the expected range, which could be a wiring or sensor fault or a real voltage problem in the pack. Which part of the pack sense 'R' covers depends on the model, so check the manufacturer data for that vehicle.

Symptoms

• Hybrid system, check engine or battery warning light on
• Reduced power or limp-home mode
• Poor or reduced electric assist and lower fuel economy
• Battery state-of-charge reading erratic or unavailable
• Hybrid system refusing to start or switching off unexpectedly
• Reduced or no regenerative braking

Possible causes

• Damaged, corroded or loose connector or wiring on the battery voltage sense circuit, giving a low or open signallikely
• Fault in the battery monitoring unit or voltage sensing circuit that reports a false low readinglikely
• Poor connection or high resistance at a high-voltage busbar or sense lead inside the battery packpossible
• Genuinely low or imbalanced cell or module voltage from a weak or degraded batterypossible
• Moisture, coolant or debris ingress in the battery pack or its sensing harnesspossible
• Low 12 V supply or poor earth to the battery control unit upsetting its readingspossible
• Internal fault or outdated software in the battery control unitrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting any other battery, cell or insulation codes.
2. Check the 12 V battery voltage and charging state, and fix any low-voltage fault before going further.
3. Look up the manufacturer's data for the model to find what sense 'R' refers to and where its sensor and wiring are.
4. Visually inspect the accessible harness and connectors for damage, corrosion, water ingress, loose pins or chafing.
5. With a scan tool, compare the live battery pack voltage and individual cell or module voltages for imbalance or an implausible reading.
6. Check the battery pack cooling air path and filters for blockage, and the pack area for signs of leaks or contamination.
7. Only a trained technician with high-voltage training, proper isolation procedures and insulated equipment should test the sense circuit and pack. Follow the manufacturer's procedure.
8. Check for software updates or technical bulletins for this model and code.

How to fix

• Repair or replace damaged wiring and clean or replace faulty connectors on the sense circuit.
• Replace the faulty battery monitoring unit or sensing component if it reports an incorrect voltage.
• Repair or tighten loose busbar or sense lead connections inside the pack, using the manufacturer's procedure.
• Rebalance, repair or replace weak battery modules or the pack where genuine voltage faults are found.
• Dry out and repair any water ingress and fix its source.
• Update the control unit software if the manufacturer lists it as a fix for this fault.

Can I keep driving?

Nearby codes

• P0B91GenericHybrid/EV Battery Voltage Sense R Circuit Range/Performance
• P0B93GenericHybrid/EV Battery Voltage Sense R Circuit High