P0D12

What it means

P0D12 is a generic powertrain code relating to the high voltage battery charging system on hybrid and electric vehicles. It indicates that the control unit has found the control circuit for negative contactor A in the charging system to be operating outside its expected range or performance. The control unit commands the contactor and compares the circuit's electrical behaviour or the contactor's feedback with what it expects, and the two do not agree.

Symptoms

• Warning light on, which may be a hybrid or EV system warning as well as the check engine light
• Vehicle will not charge from an external charge point or charges intermittently
• Charging starts and then stops part way through
• Reduced power or the vehicle going into a limited performance mode
• Vehicle will not enter ready mode or will not start
• Clicking from the high voltage battery area is absent or irregular when charging is requested

Possible causes

• Wiring fault in the contactor A control circuit, such as high resistance, chafing, or an intermittent open or shortlikely
• Corroded, loose or damaged connector terminals at the contactor, battery control unit or charger modulelikely
• Negative contactor A with a worn coil, sticking or welded contacts, or feedback that is out of rangepossible
• Low or unstable 12 volt supply or poor earth to the battery control unit or contactor circuitpossible
• Fault inside the battery management or charger control unit driver circuitrare
• Outdated or faulty control unit software where the manufacturer has published a fix for this coderare

How to diagnose

1. Read all stored codes and freeze frame data, noting whether the vehicle was charging, starting or driving when the code set, and check for other hybrid or EV battery and charging codes
2. Check the 12 volt battery condition and charging, as low voltage can cause contactor control faults
3. Make sure the high voltage system is isolated by a suitably trained person before any work beyond visual inspection, following the manufacturer's procedure
4. Visually inspect the wiring and connectors for the contactor control circuit for damage, water ingress, corrosion and pin tension
5. Check the supply, earth and control signal at the contactor circuit against the manufacturer's wiring diagram, as pin layouts vary by model
6. Measure the contactor coil resistance and check its operation and feedback against specification, using the manufacturer's procedure
7. Check for software updates or technical service bulletins for the specific model and software version
8. Clear the code and retest by attempting a charge to see if it returns

How to fix

• Repair or replace damaged wiring and correct any short, open or high resistance in the control circuit
• Clean or replace corroded or damaged connectors and terminals
• Replace the negative contactor or the battery junction assembly if it fails testing, as the manufacturer specifies
• Restore 12 volt supply and earth by charging or replacing the 12 volt battery and repairing earth connections
• Replace the battery management or charger control unit only after the wiring and contactor are proven good, then complete any required setup
• Update the control unit software if an applicable update exists for this fault

Can I keep driving?

Nearby codes

• P0D11GenericBattery Charging System Negative Contactor A Control Circuit/Open
• P0D13GenericBattery Charging System Negative Contactor A Control Circuit Low