Code
P1302
HONDA
P — Powertrain
Cylinder 2 Misfire
AI status
Completed
Completed
100%
Causes
- Faulty ignition coil or ignition module for cylinder 2
- Worn, fouled, or incorrectly gapped spark plug in cylinder 2
- Clogged, leaking, or electrically faulty fuel injector for cylinder 2
- Low compression in cylinder 2 (worn rings, valves, head gasket)
- Wiring harness or connector fault to coil or injector (open, short, corrosion)
- Vacuum leak or intake manifold gasket leak near cylinder 2
Symptoms
- Check Engine Light (CEL) illuminated
- Engine rough idle or vibration, especially at idle
- Reduced acceleration and engine power
- Poor fuel economy
- Intermittent or consistent misfire felt from engine
- Possible failed emissions test or increased exhaust smoke
What to check
- Read stored DTCs and freeze-frame data with an OBD-II scanner; confirm P1302 and note engine conditions
- Monitor live data: misfire counters (cylinder 2), RPM, ignition timing, injector pulse width, fuel trims, and O2 sensor readings
- Perform a visual inspection of spark plug, ignition coil, and connector for cylinder 2
- Swap ignition coil (or coil-on-plug) with another cylinder to see if misfire follows the coil
- Swap injector with another cylinder or use an active injector test to verify operation
- Measure fuel rail pressure and check for fuel delivery issues
Signal parameters
- Misfire count for cylinder 2 (event/second) — expected: 0 events when healthy
- Ignition coil primary resistance (Ω) and secondary performance — compare to service spec
- Injector pulse width (ms) at idle — typical: ~1–5 ms (varies by engine load and ECU)
- Fuel rail pressure (psi or kPa) — expected per vehicle spec (commonly 40–60 psi on many systems)
- Short-term/long-term fuel trim (%) — should be near 0% (within ±10%) when normal
- Cylinder compression (psi or kPa) — healthy cylinder commonly >100–140 psi depending on engine
Diagnostic algorithm
- Connect scan tool, read and record all DTCs and freeze-frame data. Confirm misfire is present on cylinder 2 (P1302 or P0302).
- Monitor live data while engine is running: cylinder 2 misfire count, fuel trims, injector pulse, and coil command.
- Visually inspect spark plug and coil for damage, carbon fouling, oil fouling, or loose connections. Replace plug if fouled or out of spec.
- Swap the ignition coil from cylinder 2 with a known-good coil from another cylinder. Clear codes and run engine. If misfire moves to the swapped cylinder, replace the coil.
- If coil swap does not move the misfire, swap the fuel injector with another cylinder or perform an injector bench/active test. Observe if misfire follows injector.
- Check wiring and connectors for the coil and injector on cylinder 2 (backprobe while cranking/running). Repair any open/short/corrosion.
- Measure fuel pressure at the rail and confirm within specification; inspect fuel supply and filter if low.
- Perform a compression test and/or leak-down test on cylinder 2 and compare to other cylinders. Address mechanical failures if compression is low.
- Inspect intake manifold gasket and nearby vacuum lines for leaks (use smoke test if available). Repair leaks and retest.
- After repairs, clear codes and road-test under varied load. Re-scan for return of P1302. If problem persists, consider ECU/PCM diagnostics or professional diagnosis.
Likely causes
- Failed ignition coil on cylinder 2
- Spark plug fouled or degraded in cylinder 2
- Fuel injector stuck or not pulsing on cylinder 2
- Open/short in coil/injector wiring or poor connector contact
- Low cylinder compression or valve issue on cylinder 2
Fault status
Status
P1302 — Cylinder 2 Misfire: ECM detected misfire events on cylinder #2. Check ignition, fuel, mechanical condition, and associated wiring/connectors.
Repair difficulty: Medium
Diagnostic time: 1.0 - 2.5 hours
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