Code
P0302
GWM
P — Powertrain
- The order of ignition of 2 cylinders is broken
Views:
UK: 14
EN: 28
RU: 19
AI status
Completed
Completed
100%
Causes
- Faulty ignition coil for cylinder 2
- Worn or fouled spark plug (cylinder 2)
- Failed or leaking fuel injector on cylinder 2
- Low compression or mechanical problem in cylinder 2 (valve, piston, rings)
- Vacuum leak or intake manifold leak affecting cylinder 2
- Wiring/connectors or ECU driver fault for injector or coil circuit
Symptoms
- Malfunction Indicator Lamp (MIL/Check Engine) illuminated
- Rough idle or vibration at idle
- Loss of power, hesitation or poor acceleration
- Reduced fuel economy
- Noticeable misfire at certain RPM/loads
- Possible increased exhaust smell or emissions test failure
What to check
- Read and record freeze frame data and stored codes with a scanner
- Monitor live data: misfire counters, fuel trims (STFT/LTFT), RPM, injector pulse widths, ignition dwell
- Check for pending/other related DTCs (e.g., other cylinder misfires, fuel system codes)
- Visually inspect spark plug, ignition coil/lead and wiring on cylinder 2 for damage or corrosion
- Swap coil/spark plug/injector with another cylinder to see if code follows component (isolates coil/plug/injector)
- Perform fuel pressure test to verify system pressure and regulator operation
Signal parameters
- Misfire counter for cylinder 2 (events/min or counts)
- Short-term/long-term fuel trims (STFT/LTFT) — ideally near 0%, large positive values indicate lean condition
- Injector pulse width (ms) at tested load/RPM — should be consistent with other cylinders
- Ignition primary voltage (near battery voltage) and coil dwell time (manufacturer-specific)
- Compression pressure (psi or kPa) — cylinder 2 should be within ~10% of other cylinders
- Fuel rail pressure (kPa/bar) within specified range
Diagnostic algorithm
- Connect OBD-II scan tool; record codes and freeze frame data.
- Verify misfire is current; monitor misfire counters and fuel trims while engine runs at idle and under load.
- Visually inspect spark plug and coil on cylinder 2; replace spark plug if fouled or out of spec.
- If available, swap the ignition coil from cylinder 2 with another cylinder. Clear codes and run engine. If misfire moves to swapped cylinder, replace the coil.
- If coil swap negative, swap injectors between cylinder 2 and another cylinder (or bench-test injector). If misfire follows injector, replace injector.
- Check wiring and connectors for cylinder 2 (ignition and injector): test resistance, continuity and operation of driver circuits; repair any damaged harness or connector.
- Measure fuel rail pressure and compare to specification; inspect for clogged fuel filter or weak pump if pressure low.
- Perform compression or leak-down test on cylinder 2; if low, inspect for mechanical damage (valve, head gasket, rings) and repair as needed.
- Perform a smoke test or carefully inspect for vacuum/intake leaks near cylinder 2 that could cause lean condition.
- After repairs, clear codes and road-test to confirm misfire is resolved; rerun live-data checks to verify proper operation.
Likely causes
- Faulty ignition coil or spark plug on cylinder 2
- Clogged or failed fuel injector on cylinder 2
- Low compression or mechanical fault in cylinder 2
- Wiring/connectors (coil/injector) or intermittent open/short
Fault status
Status
Misfire detected on cylinder 2 — ignition/fuel delivery or mechanical issue affecting cylinder 2.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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