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P0205

Fuel injector failure, Powertrain Control Module (PCM) failure, Wiring issue.

  • Audi
  • Powertrain
  • Generic code
  • Medium severity

How this code is built

P
SystemPowertrain
0
Defined bySAE, the same on every car
2
AreaFuel and air metering (injector circuit)
05
FaultThe specific fault in that area

What it means

On this Audi, P0205 means the engine control unit has detected a fault in the cylinder 5 fuel injector circuit. It set the code because the injector's electrical signal or current did not match what it expected, which points to an open circuit, a short, a failed injector or, rarely, a control unit driver fault. Cylinder 5 only exists on five-, six-, eight- and larger engines, and the cylinder numbering depends on the engine.

Symptoms

  • Engine management light on
  • Rough idle or misfire, mainly on one cylinder
  • Hesitation or loss of power under acceleration
  • Hard starting or extended cranking
  • Smell of unburnt fuel or poor fuel economy
  • Engine running in a reduced-power mode

Possible causes

  • Faulty cylinder 5 injector (open or shorted coil)likely
  • Damaged, corroded or loose injector connector or terminalslikely
  • Wiring fault between the injector and control unit (open circuit, chafing, short to earth or supply)possible
  • Poor power supply or earth affecting the injector circuit, such as a relay, fuse or earth point faultpossible
  • Water or oil contamination in the connector or harnesspossible
  • Fault in the engine control unit injector driverrare

How to diagnose

  1. Read all stored and pending codes and the freeze frame data, noting engine load, temperature and rpm when the fault set, and look for related misfire or other injector codes.
  2. Confirm which physical cylinder is number 5 on this particular engine, as the layout varies by model and engine.
  3. Visually inspect the cylinder 5 injector connector and harness for damage, heat, chafing, oil, water ingress and bent or corroded pins.
  4. With the ignition off and the connector unplugged, measure the injector coil resistance and compare it with the manufacturer specification for that engine.
  5. Check the injector circuit wiring for continuity and for shorts to earth or supply, and check the supply voltage and earth at the connector.
  6. Use a scope or suitable test equipment to confirm the control unit is sending the injector drive signal, following the manufacturer procedure for the engine type.
  7. Where the engine allows it and the manufacturer procedure permits, compare readings with a known good injector, taking care with high-pressure fuel systems.
  8. Check the relevant fuses, relays and control unit connector pins before suspecting the control unit itself.

How to fix

  • Repair or replace the damaged wiring, terminals or connector on the cylinder 5 injector circuit.
  • Replace the faulty injector, using new seals and following the correct fitting procedure for the engine.
  • Restore any faulty power supply or earth connection, including replacing a failed relay or fuse after finding why it failed.
  • Dry out, clean and properly seal a contaminated connector, and replace it if corrosion has damaged the terminals.
  • Replace or repair the engine control unit only after the wiring and injector are proven good, and have it programmed to the vehicle.

Can I keep driving?

Medium severity

The car can usually be driven a short distance to a workshop, but get it checked soon. A dead injector causes misfires and unburnt fuel can overheat and damage the catalytic converter, so avoid hard driving, and stop if the engine runs very roughly or the warning light flashes.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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