P02C7 - Cylinder 10 Fuel Trim at Max Limit - Lean Correction (System Rich)
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P02C7 is stored when the Engine Control Module (ECM) can no longer compensate for an overly rich air-fuel mixture in cylinder 10. The system has reached its negative fuel trim limit, meaning the ECU is trying to reduce fuel delivery to the maximum extent allowed, yet the cylinder remains rich. This is typically monitored through crankshaft speed fluctuations and oxygen sensor (Lambda) feedback reflecting a lack of residual oxygen in the exhaust stroke for that specific cylinder.
Possible Causes
Leaking or fouled fuel injector for cylinder 10
Faulty ignition coil or spark plug causing incomplete combustion
Mechanical engine issue (valves/compression) on cylinder 10
Defective ECU injector driver (stuck in open state)
Symptoms
Recommended Solution
- STEP 1: Visually inspect wiring for cylinder 10 injector and ignition coil. Check for external fuel leaks around the fuel rail.
- STEP 2: Inspect the spark plug on cylinder 10. A wet plug indicates a leaking injector or lack of spark. Measure ignition coil resistance.
- STEP 3: Perform an injector balance/leak-down test. Normal injector resistance is typically 12-16 Ohms (high-Z) or 2-5 Ohms (low-Z). Use an oscilloscope to verify injector pulse width and inductive kick.
- STEP 4: If the injector is mechanically faulty or leaking, replace the injector for cylinder 10. Clear codes and reset fuel trim adaptations.
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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