Code
P1302
INFINITI
P — Powertrain
Cylinder 2 Misfire
AI status
Completed
Completed
100%
Causes
- Faulty ignition coil or coil pack for cylinder 2
- Worn or fouled spark plug in cylinder 2
- Clogged, leaking, or electrically-faulty fuel injector for cylinder 2
- Low compression or mechanical engine problem (valve, piston, ring) on cylinder 2
- Vacuum leak or intake manifold gasket leak near cylinder 2
- Low fuel pressure or weak fuel pump
Symptoms
- Check Engine/MIL illuminated
- Rough idle or vibration at idle
- Reduced engine power and acceleration
- Poor fuel economy
- Engine runs unevenly or stumbles under load
- Possible engine backfire or increased exhaust emissions
What to check
- Read freeze frame and live data with a scan tool (misfire counts, fuel trims, O2 sensors, misfire cylinder ID)
- Visually inspect spark plug, ignition coil, and wiring/connector for cylinder 2
- Swap coil or spark plug from cylinder 2 with another cylinder to see if code follows
- Swap injector with another cylinder or test injector operation (resistance and pulse) with scan tool
- Measure fuel rail pressure and check for adequate fuel supply
- Perform a wet/dry compression test or cylinder leak-down test on cylinder 2
Signal parameters
- Misfire counters per cylinder (counts/sec or per drive cycle)
- Short-term and long-term fuel trim (STFT/LTFT)
- O2/AFR sensor voltages or wideband lambda
- Crankshaft and camshaft position sensor waveforms and correlation
- Ignition coil primary/secondary current or voltage (dwell, spark energy)
- Injector pulse width and injector resistance
Diagnostic algorithm
- Retrieve DTCs and freeze-frame data; note conditions when misfire occurred. Clear codes and reproduce if safe.
- Visually inspect ignition components and wiring on cylinder 2 (coil, plug, boot, connector). Replace visibly damaged parts.
- Swap the coil and/or spark plug from cylinder 2 with a known-good cylinder. If the misfire code follows the component, replace it.
- Test injector: check resistance, listen for injector operation, and/or swap injectors between cylinders to isolate. Use a noid light or scope if needed.
- Check fuel system: measure fuel rail pressure and inspect for clogged filter or weak pump.
- Perform compression or leak-down test on cylinder 2 to rule out mechanical faults (valve seating, piston rings, head gasket).
- Inspect intake/exhaust for leaks and ensure intake runner vacuum at cylinder 2 is normal (smoke test or visual).
- Verify cam/crank position sensors and timing correlation with a scope; correct timing if slipped or damaged.
- Inspect wiring harness and connectors for corrosion, shorts, and proper grounding. Wiggle-test connectors while monitoring live data for intermittent faults.
- If all hardware checks are good, check for PCM software updates or intermittent PCM issues; consult OEM technical service bulletins.
- After repair, clear codes and perform a road test/loaded conditions to confirm the misfire is resolved and that no related codes return.
Likely causes
- Faulty ignition coil or spark plug (most common)
- Faulty or clogged fuel injector
- Wiring/connectors to coil or injector (intermittent short/open)
- Low cylinder compression or valve issue
- Fuel pressure problem or contamination
Fault status
Status
P1302 — Cylinder 2 Misfire. The engine control module detected that cylinder 2 is misfiring. Possible causes include ignition, fuel delivery, compression, timing, or wiring/sensor faults.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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