P02F4
Cylinder 7 Injector Circuit Range/Performance.
- Generic
- 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)
- F4
- FaultThe specific fault in that area
What it means
P02F4 is a generic code meaning the engine control unit has detected that the cylinder 7 fuel injector circuit is not performing as expected. The control unit monitors the injector driver circuit and its response, and has seen a reading outside the expected range without necessarily seeing a complete open or short circuit. It only applies to engines with at least seven cylinders, and the exact monitoring method depends on the engine and manufacturer.
Symptoms
- Engine misfire or rough running, especially at idle
- Loss of power or hesitation under acceleration
- Engine management warning light on
- Poor fuel economy
- Fuel smell or raw fuel in the exhaust
- Engine running in a reduced power mode
Possible causes
- Wiring or connector fault in the cylinder 7 injector circuit, such as high resistance, corrosion or a loose pinlikely
- Faulty cylinder 7 injector with internal winding resistance out of range or sticking operationlikely
- Damaged, chafed or heat-affected harness near cylinder 7 causing intermittent short to earth or supplypossible
- Low or unstable supply voltage to the injectors from a poor earth, weak battery or charging problempossible
- Fault in the injector driver within the engine control unitrare
- Outdated control unit software where the manufacturer has issued a correction for injector circuit monitoring (model dependent)rare
How to diagnose
- Read all stored and pending codes and the freeze frame data to see engine load, speed, temperature and voltage when the fault set, and check for related misfire or other injector codes.
- Visually inspect the cylinder 7 injector connector and harness for damage, corrosion, oil contamination, heat damage and secure fitment.
- Check battery condition and charging voltage, and inspect the main earth connections.
- Use a scan tool to check misfire counters and, if supported, run an injector balance or cylinder contribution test on cylinder 7.
- Measure the cylinder 7 injector winding resistance and compare it with the manufacturer's specification for that engine.
- With the connector disconnected, check the wiring between the injector and the control unit for continuity, high resistance and shorts to earth or supply, following the wiring diagram.
- Swap the cylinder 7 injector with another cylinder if the design allows, clear the code and see whether the fault follows the injector.
- Check for any manufacturer software updates or technical bulletins relating to injector circuit diagnostics for the specific model.
How to fix
- Repair or replace damaged wiring and renew corroded or loose connector terminals.
- Replace the cylinder 7 injector if it is electrically or mechanically faulty, following the manufacturer's procedure and any coding requirements.
- Correct power supply or earth faults, and replace a weak battery or faulty charging component.
- Replace or repair the engine control unit only if the driver circuit is confirmed faulty after all wiring and injector checks.
- Apply a manufacturer software update if an outdated calibration is a documented cause for that model.
Can I keep driving?
Short, gentle journeys are possible, but get it checked soon. A misfiring or incorrectly fuelling cylinder can damage the catalytic converter and may cause the engine to run poorly or stall. If the engine runs very roughly, the warning light flashes or there is a strong fuel smell, stop driving and arrange recovery.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.