P02B5
Cylinder 7 - Injector Leaking.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- B5
- FaultThe specific fault in that area
What it means
P02B5 is the generic code for a leaking fuel injector on cylinder 7, so it only applies to engines with at least seven cylinders. The engine control unit sets it when it detects signs that cylinder 7 is receiving more fuel than commanded, or that the injector is dripping or not sealing when it should be closed. The exact detection method depends on the manufacturer and engine, and may involve fuel trim, fuel rail pressure behaviour or misfire and combustion monitoring.
Symptoms
- Engine management light on
- Rough idle or misfire on cylinder 7, especially after a hot restart
- Long cranking or hesitant starting after the car has been standing
- Smell of unburnt fuel from the exhaust
- Poor fuel economy
- Possible fuel dilution of the engine oil, with a fuel smell from the dipstick
Possible causes
- Cylinder 7 injector nozzle or needle sticking or not sealing (wear, deposits or contamination)likely
- Damaged or hardened injector seal or O-ring allowing fuel to leak past into the cylinder or intakepossible
- Fuel pressure too high due to a faulty pressure regulator or return system fault, forcing injectors open or leakingpossible
- Wiring or connector fault on the cylinder 7 injector circuit causing incorrect injector operationpossible
- Contaminated or poor-quality fuel causing injector deposits and poor sealingpossible
- Fault in the engine control unit injector driverrare
How to diagnose
- Read all stored and pending codes and review freeze frame data, noting engine temperature, load and fuel trim values at the time the code set.
- Check for other related codes such as misfire, fuel trim or fuel pressure faults, as these help narrow down the cause.
- Inspect the cylinder 7 injector wiring and connector for damage, corrosion, chafing or poor pin tension.
- Look for external fuel leaks around the injector and fuel rail, and check the oil for a fuel smell or raised level.
- Monitor fuel rail pressure and short and long term fuel trims at idle and after shutdown, comparing against manufacturer specifications for the engine.
- Perform a fuel pressure leak-down or pressure hold test where the engine design allows, and check regulator and return operation.
- Check the injector electrical resistance and driver waveform against specification, and compare with neighbouring cylinders.
- Swap the cylinder 7 injector with another cylinder if the procedure allows, to see whether the fault follows the injector.
How to fix
- Replace the leaking cylinder 7 injector, or the full set if the manufacturer advises, and renew its seals.
- Repair or replace damaged wiring or connectors on the injector circuit.
- Repair or replace the fuel pressure regulator or any faulty part of the fuel supply or return system.
- Drain contaminated fuel, replace the fuel filter where fitted, and refill with good quality fuel.
- Change the engine oil and filter if fuel dilution is confirmed.
- Apply any manufacturer software update for the engine control unit only if an outdated calibration is a known cause for that engine.
Can I keep driving?
Limit driving and have it checked promptly. A leaking injector can wash fuel past the piston rings, diluting the oil, and in serious cases can cause hydraulic lock or damage the catalyst.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.