P0B6D

What it means

P0B6D means the hybrid or EV battery control unit has found a fault in voltage sense circuit 'K', one of the circuits that measure voltage across a section of the high-voltage battery pack. It usually sets when the reading is out of range, missing, erratic, or does not agree with the other sense circuits or the total pack voltage. Which battery section circuit K covers depends on the make, model and pack design.

Symptoms

• Hybrid or EV system warning light, or a general malfunction indicator lamp, on the dashboard
• Reduced power or limp-home mode
• Reduced or no electric assist or regeneration
• Poor or erratic state-of-charge display
• Engine running more often than normal on a hybrid
• Car refusing to enter ready mode in some cases

Possible causes

• Damaged, corroded or loose connector or terminal on the battery voltage sense harnesslikely
• Open circuit, short or chafed wiring in the sense circuit between the battery cells or modules and the monitoring unitlikely
• Fault in the battery monitoring or battery control unit's input for that circuitpossible
• Genuine voltage imbalance or a weak cell block or module in the pack, giving an implausible readingpossible
• Low or unstable 12 V supply or poor earth to the battery control unit causing false readingspossible
• Moisture, coolant or debris ingress in the battery pack or its connectorsrare
• Outdated control unit software where the manufacturer has a known fix for the faultrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting any other battery voltage, temperature or insulation codes, and check for manufacturer bulletins for the model.
2. Check the 12 V battery condition and charging voltage, and the earths to the battery control unit, as low supply can cause false sense faults.
3. Using live data, compare the voltage for each battery block or sense circuit with the others and with total pack voltage. Look for one reading that is missing, stuck, or far from the rest.
4. Inspect the accessible low-voltage connectors and harness for damage, corrosion, water ingress, pushed-out pins or rubbing. Do not touch any orange high-voltage cabling or components unless trained.
5. Any work involving the pack or high-voltage system must be done only by a trained technician following the manufacturer's isolation and safe-working procedure.
6. Check the sense circuit continuity, resistance and wiring against the model's wiring diagram, with the system isolated as required.
7. If the wiring is good, check the pack for a real cell or module imbalance using the manufacturer's recommended method.
8. Clear the code and road test, watching whether it returns and whether the reading drops out when the harness is moved.

How to fix

• Repair or replace damaged wiring, terminals or connectors in the voltage sense circuit.
• Replace the battery sense harness if it is internally faulty or damaged.
• Replace the battery monitoring or control unit if its input is confirmed faulty, and complete any required setup.
• Rebalance, repair or replace the affected battery module or pack if a real voltage fault is found.
• Restore a healthy 12 V supply and good earths by replacing the 12 V battery or repairing the connections.
• Apply a manufacturer software update if a known calibration fault is confirmed for that model.

Can I keep driving?

Nearby codes

• P0B6CGenericHybrid/EV Battery Voltage Sense J Circuit Intermittent/Erratic
• P0B6EGenericHybrid/EV Battery Voltage Sense K Circuit Range/Performance