P02F3 - Cylinder 7 Injector - Contribution/Balance Fault
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P02F3 indicates that the Engine Control Unit (ECU) has detected an imbalance in the fuel contribution from cylinder number 7. The ECU monitors the crankshaft acceleration via the Crankshaft Position (CKP) sensor after each firing event to ensure each cylinder contributes equally to the total engine torque. If cylinder 7 fails to meet the expected acceleration threshold, the ECU flags a contribution/balance fault. This may be caused by restricted fuel flow, a mechanical issue within the injector, or an electrical circuit problem affecting the injector duty cycle.
Possible Causes
Clogged or dirty fuel injector (Cylinder 7)
High resistance or corrosion in the electrical connector/harness
Internal mechanical failure of the injector
Low engine compression in cylinder 7
Faulty Engine Control Unit (ECU) or software glitch
Symptoms
Recommended Solution
- STEP 1: Inspect the electrical connector for injector 7 for corrosion or loose pins. Clean as necessary.
- STEP 2: Measure the internal resistance (ohms) of the injector using a multimeter. Normal values are typically 12–16 Ohms (check OEM specs). Compare with adjacent injectors.
- STEP 3: Perform a fuel trim analysis and a cylinder contribution test using a scan tool. Check if the fault moves by swapping the injector to another cylinder.
- STEP 4: If the injector is confirmed faulty/clogged, replace the injector or perform professional ultrasonic cleaning.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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