P02A5
Cylinder 3 - 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)
- A5
- FaultThe specific fault in that area
What it means
P02A5 means the engine control unit has detected that the fuel injector on cylinder 3 is leaking, meaning fuel is getting into the cylinder when the injector should be closed. The ECU typically infers this from fuel rail pressure decay, fuel trim behaviour, or misfire and combustion data for that cylinder. The exact detection method depends on the engine and fuel system, so check the manufacturer's information for the specific model.
Symptoms
- Engine warning light on
- Long cranking or hard starting, especially when hot
- Rough idle or misfire on cylinder 3
- Smell of fuel from the exhaust or in the engine bay
- Fuel dilution of the engine oil (rising oil level or fuel smell on the dipstick)
- Poor fuel economy or hesitation under load
Possible causes
- Cylinder 3 injector sticking open or leaking at the nozzle tiplikely
- Carbon or debris holding the injector needle off its seatlikely
- Damaged or worn injector seals or O-rings allowing fuel past (design dependent)possible
- Excessive fuel pressure from a faulty pressure regulator or pressure control valvepossible
- Wiring or connector fault on the cylinder 3 injector circuit causing incorrect injector operationpossible
- Mechanical fault on cylinder 3 (for example low compression) wrongly pointing to the injectorrare
- Outdated or faulty ECU software where the manufacturer has issued a known fixrare
How to diagnose
- Read all stored and pending codes and note the freeze frame data (engine temperature, load, fuel pressure, fuel trims) for when the fault set.
- Check for related codes such as misfires, fuel trim, or rail pressure faults, and look for manufacturer bulletins for the engine.
- Inspect the cylinder 3 injector connector and wiring for damage, corrosion, or poor pin tension.
- Check the engine oil level and smell for fuel dilution, as a leaking injector can wash fuel into the sump.
- Monitor live fuel pressure and trims, and check whether rail pressure drops abnormally quickly after switching off (procedure depends on the fuel system).
- Check the injector electrical resistance and waveform against the manufacturer's specification.
- Swap the cylinder 3 injector with another cylinder (where the design allows) and see whether the fault follows the injector.
- Carry out a compression test and inspect the spark plug on cylinder 3 for fuel soaking or fouling.
How to fix
- Replace the leaking cylinder 3 injector, and renew its seals and any washers or O-rings as the manufacturer requires.
- Replace all injectors if they are worn or of the same age and the manufacturer recommends it.
- Repair or replace damaged wiring or connectors on the injector circuit.
- Replace a faulty fuel pressure regulator or pressure control valve if pressure is found to be out of specification.
- Change the engine oil and filter if fuel dilution is confirmed.
- Apply a manufacturer-issued ECU software update only if a bulletin identifies outdated software as the cause.
Can I keep driving?
Limit driving and get it checked promptly. A leaking injector can wash the cylinder walls, dilute the engine oil, and damage the engine or catalytic converter, and in severe cases it risks hydraulic lock or fire.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.