P0302 — Cylinder 2 Misfire Detected
P0302 sets when the ECM detects misfire events on cylinder 2 exceeding the calibrated threshold using crankshaft speed fluctuations. Always swap the coil with another cylinder first — if the misfire follows the coil, the coil is bad. On many V6 engines cylinder 2 is on the back bank and harder to access; use the correct tools.
Fault Overview
Failed spark plug or ignition coil on cylinder 2, clogged or leaking injector, low compression, wiring fault specific to cylinder 2, carbon tracking, vacuum leak affecting cylinder 2, and oil in the spark-plug well are the primary causes. Direct-injection engines often have carbon buildup that contributes to misfires on specific cylinders.
Engine & Platform Coverage
Symptoms
- •P0302
- •cylinder 2 misfire
- •#2 cylinder misfire
- •P0302 Honda
- •P0302 Toyota
- •P0302 Ford
- •P0302 Chevy
- •rough idle cylinder 2
Possible Causes
- 1.Failed spark plug or ignition coil on cylinder 2
- 2.Clogged or leaking injector on cylinder 2
- 3.Low compression on cylinder 2
- 4.Wiring fault specific to cylinder 2 coil or injector
- 5.Carbon tracking
- 6.Vacuum leak affecting cylinder 2
- 7.Oil in the spark-plug well
Wiring & Circuit Notes
Inspect coil-on-plug connector and injector connector for cylinder 2. Check for oil intrusion in the plug well and chafed wiring. Verify power, ground, and control signals under load.
DVOM Specs & Sensor Tests
Coil primary resistance and current ramp. Injector resistance and balance test. Relative compression or leak-down on cylinder 2. Scope patterns for ignition secondary and injector pulse width.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
6 steps locked behind Technician Mode- 1Step 1 — Confirm Misfire Is Isolated to Cylinder 2: Confirm misfire is isolated to cylinder 2 via scan data misfire counters.
- 2Step 2 — Remove and Inspect the Spark Plug: Remove and inspect the cylinder 2 spark plug for fouling, wear, or damage.
- 3Step 3 — Swap the Coil with Another Cylinder: Swap the coil with another cylinder and recheck misfire counts. If the misfire follows the coil, replace it.
- 4Step 4 — Test or Swap the Injector: Test or swap the cylinder 2 injector if ignition components are proven good.
- 5Step 5 — Perform Relative Compression or Leak-Down Test: Perform a relative compression or leak-down test on cylinder 2.
- 6Step 6 — Inspect Wiring and Connectors: Inspect wiring and connectors specific to cylinder 2 coil and injector.
- 7Step 7 — Repair and Verify Zero Misfire Counts: Repair the failed component and verify zero misfire counts on a road test.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Replace spark plug and/or coil $40–200; clean or replace injector $100–450; repair valve-cover gasket $100–400; address compression issues $500–2,000+.
Related Codes & Pages
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Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.