P02F5
Cylinder 8 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)
- F5
- FaultThe specific fault in that area
What it means
P02F5 is a generic powertrain code meaning the engine control unit has detected that the cylinder 8 fuel injector circuit is not performing as expected. The control unit monitors the injector driver circuit and its electrical response, and has seen a value outside the expected range without necessarily seeing a complete open or short circuit. The exact monitoring method and set conditions vary by manufacturer and engine.
Symptoms
- Engine misfire or rough running, especially at idle
- Malfunction indicator lamp on
- Reduced power or hesitation under load
- Poor fuel economy
- Hard starting or extended cranking
- Fuel smell or raised exhaust odour if the injector is leaking or stuck open
Possible causes
- Faulty cylinder 8 injector (internal winding resistance out of range or sticking)likely
- Damaged, chafed or corroded wiring between the injector and the control unitlikely
- Poor connection at the injector plug or control unit connector (loose, corroded or spread terminals)likely
- Low or unstable supply voltage to the injector circuit, for example from a weak battery, charging fault or poor earthpossible
- Intermittent short to earth or to supply on the injector control or feed wirepossible
- Fault inside the engine control unit injector driverrare
- Outdated or faulty control unit calibration, where the manufacturer has issued an update for this faultrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting engine speed, load, temperature and battery voltage when the fault set; look for related misfire codes on cylinder 8.
- Check battery condition, charging voltage and main earth connections, as low voltage can cause injector circuit range faults.
- Visually inspect the cylinder 8 injector connector and wiring for heat damage, chafing, oil contamination, corrosion and pushed-back terminals.
- Wiggle-test the harness and connector with the engine running or while monitoring live data to see whether the fault or a misfire appears.
- Measure the cylinder 8 injector winding resistance and compare it with the specification for that engine; also compare with other cylinders.
- Check the injector feed and control wires for continuity, and for shorts to earth or supply, following the wiring diagram for the model.
- Use a scan tool or scope to check the injector activation signal and current pattern on cylinder 8 against a known good injector.
- Check for any manufacturer technical bulletins or calibration updates relating to this code for the specific engine.
How to fix
- Replace the cylinder 8 injector if its resistance or operation is faulty, following the correct procedure for seals and fuel system safety.
- Repair or replace damaged wiring between the injector and control unit.
- Clean, repair or replace corroded or loose connectors and terminals.
- Correct battery, charging or earth faults that cause low or unstable voltage.
- Apply a manufacturer-issued calibration update only if an outdated calibration is confirmed as the cause.
- Have the control unit tested and repaired or replaced only after the injector, wiring and supply have all been proven good.
Can I keep driving?
The car can usually be driven carefully for a short time, but get it checked soon. A misfiring or leaking injector can wash oil from the cylinder wall and overheat the catalytic converter, so avoid heavy loads and stop if the engine runs very roughly or the warning lamp flashes.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.