P0B8E

What it means

P0B8E means the hybrid/EV battery control unit saw a signal above the expected range on voltage sense circuit Q, which is one of the monitoring channels for the high-voltage battery. The control unit compares each sense reading with plausible limits and with other channels. A reading too high, such as a shorted-high or open circuit, sets the code. Which cell block or module 'Q' refers to depends on the model and battery pack design.

Symptoms

• Hybrid or EV system warning light on, often with the main warning light
• Reduced power or the car going into a limited performance mode
• Hybrid assist or electric-only driving reduced or unavailable
• Poor or erratic state-of-charge reading
• Engine running more than normal on a hybrid
• Car refusing to enter ready mode in some cases

Possible causes

• Poor connection or corrosion at the battery voltage sense connector or terminalslikely
• Damaged, chafed or open-circuit sense wiring between the battery cells or modules and the battery monitoring unitlikely
• Fault inside the battery monitoring or battery control unitpossible
• Sense wire shorted to a higher voltage source, such as another circuitpossible
• Imbalanced or failing cell block or module giving an out-of-range readingpossible
• Moisture or coolant ingress in the battery pack affecting the sensing circuitrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data; note whether other battery voltage sense or cell balance codes are present.
2. Check the manufacturer's information for which cell block or module sense channel Q covers on this model.
3. Follow the manufacturer's high-voltage safety procedure before any work near the pack: only trained technicians should proceed, with the system isolated.
4. Inspect the battery monitoring connectors and the visible harness for corrosion, bent pins, water ingress, chafing or heat damage.
5. View live data for all voltage sense channels and compare channel Q with its neighbours and the total pack voltage.
6. Check continuity and insulation of the sense circuit, and look for shorts to other circuits, using the wiring diagram.
7. Check cell block or module voltages and balance with the manufacturer's procedure to rule out a genuine battery fault.
8. If the wiring and battery check out, test the monitoring unit's supply, grounds and communication before condemning it.

How to fix

• Clean or replace corroded or damaged connectors and terminals on the sense circuit.
• Repair or replace the damaged sense wiring or the section of harness affected.
• Replace the battery monitoring or control unit if it is confirmed faulty, and complete any manufacturer setup.
• Rebalance, repair or replace the affected cell block or module as the manufacturer specifies.
• Dry out and repair any water ingress, and fix its source, before clearing the code and retesting.

Can I keep driving?

Nearby codes

• P0B8DGenericHybrid/EV Battery Voltage Sense Q Circuit Low
• P0B8FGenericHybrid/EV Battery Voltage Sense Q Circuit Intermittent/Erratic