P0D16
Battery Charging System A High Voltage Interlock Circuit Performance.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- D
- AreaReserved
- 16
- FaultThe specific fault in that area
What it means
P0D16 means the control unit monitoring the battery charging system has found a performance fault in the high voltage interlock circuit for charging system A. The interlock is a low-voltage safety loop that proves the high voltage connectors and covers in the charging path are closed and secure. The code sets when the loop signal is intermittent, out of range or does not match what the control unit expects. Exact circuit layout and which connectors are in the loop depend on the vehicle.
Symptoms
- Hybrid or electric system warning light or message on the dashboard
- Vehicle will not charge, or charging starts and then stops
- Reduced power or the car refuses to go into ready mode
- Intermittent charging faults that come and go with vibration or temperature
- Charging port or charging cable not recognised
Possible causes
- Loose, corroded or poorly seated connector in the interlock loop, such as at the charger, charge port or high voltage batterylikely
- Damaged, chafed or pinched interlock wiring, or high resistance in the looplikely
- Charge port, on-board charger or high voltage junction cover not fully fitted, or an interlock switch or contact worn or damagedpossible
- Water ingress or contamination in a high voltage connector or the charge portpossible
- Fault in the charger or battery control unit that monitors the looprare
- Outdated or faulty control unit software, only where the manufacturer lists it as a known cause for the modelrare
How to diagnose
- Only trained and qualified high voltage technicians should work on this system. Follow the manufacturer's procedure to isolate and prove the high voltage system dead before opening anything.
- Read all stored and pending codes and the freeze frame data, noting whether the fault happened during charging, driving or at start-up. Look for related charging or isolation codes.
- Check for manufacturer service bulletins or software updates for the model and code.
- Visually inspect the charge port, its seals and the interlock-related connectors for damage, moisture, corrosion, bent pins or incomplete seating.
- Check that the high voltage covers and connectors in the charging path are correctly fitted and latched.
- Inspect the interlock wiring for chafing, pinching, heat damage or previous repairs, and wiggle-test the harness while watching live data for the loop status.
- With the system isolated, test the interlock loop for continuity and resistance against the manufacturer's specification.
- If the wiring and connectors prove good, check the supply, ground and signal at the monitoring control unit before suspecting the unit itself.
How to fix
- Clean, reseat or replace faulty interlock connectors and terminals, making sure latches lock fully.
- Repair or replace damaged interlock wiring, using the approved method.
- Refit or replace high voltage covers, charge port components or interlock switches that are loose, worn or damaged.
- Dry out and treat any water ingress, and replace seals or components that cannot be restored.
- Update the control unit software if the manufacturer lists it as a fix, or replace the control unit if it is confirmed faulty.
Can I keep driving?
This is a safety circuit on a high voltage system, so avoid charging until it is checked. If the car drives normally with no warnings or loss of power, keep trips short and go straight to a qualified workshop. Do not drive if there are warnings of reduced power or high voltage faults.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.