P06D1
Internal Control Module Ignition Coil Control Performance.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 6
- AreaComputer and output circuits
- D1
- FaultThe specific fault in that area
What it means
P06D1 is a generic code meaning the engine control unit has found a performance problem in its own internal ignition coil control circuitry. The unit's self-monitoring saw the coil drive output behave differently from what it commanded, or the internal check failed. This points to the control unit itself, its power and ground supply, or the coil control circuits it monitors.
Symptoms
- Engine warning light on
- Misfire or rough running, especially under load
- Hesitation or loss of power
- Hard starting or intermittent no-start
- Engine running in a reduced-power mode
- Other misfire or coil circuit codes stored alongside
Possible causes
- Faulty or poor power or earth supply to the engine control unit (corroded, loose or damaged connections, fuse or relay fault)likely
- Wiring or connector fault in the ignition coil control circuits (chafed, shorted, open circuit, water ingress)likely
- Faulty ignition coil or coil driver stage drawing abnormal current or giving a faulty feedback signal (depends on engine and coil design)possible
- Low or unstable battery or charging system voltage during starting or runningpossible
- Outdated control unit software with a known coil control monitoring fault (model dependent)possible
- Internal failure of the engine control unitrare
How to diagnose
- Read all stored codes and freeze frame data, noting engine load, speed and battery voltage when the code set, and check for misfire or coil circuit codes.
- Check battery condition and charging voltage, and confirm the voltage stays stable during cranking and running.
- Visually inspect the ignition coil connectors, wiring and the engine control unit connector for damage, corrosion, moisture or heat damage.
- Check the control unit fuses, relays, power feeds and earth connections for voltage drop under load.
- Look at live data for misfire counts per cylinder and any coil status or dwell data the vehicle provides.
- Swap a suspect coil with another cylinder, if the design allows, and see whether the fault or misfire follows it.
- Test the coil control wiring for continuity, shorts to earth or supply, and resistance against the manufacturer's data.
- Check for any manufacturer software updates or technical bulletins relating to this code for the specific model and engine.
How to fix
- Repair or clean power, earth and connector faults at the control unit and in the supply circuits.
- Repair or replace damaged coil control wiring and connectors.
- Replace any faulty ignition coil, and check the spark plugs at the same time as they can overload a coil.
- Restore the battery and charging system to good condition.
- Apply a manufacturer software update if one exists for a known cause on that model.
- Replace or repair the engine control unit only after power, wiring and coils are proven good, and have it coded to the vehicle as required.
Can I keep driving?
Short, gentle journeys are usually possible, but get it checked soon because misfires can damage the catalytic converter and the car may stall or lose power. If the engine is misfiring badly, the warning light is flashing or the car is in limp mode, stop driving and arrange recovery.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.