Stop if MIL flashing. Steady MIL: repair within 1-2 days. P0302 means the ECM detected a misfire specific to cylinder 2, confirmed by crankshaft speed variation analysis. The most common causes are a worn spark plug, failed coil-on-plug ignition coil, or faulty fuel injector on cylinder 2.
What P0302 means
The ECM monitors crankshaft rotational speed variations every 200 and 1000 crankshaft revolutions using both the crankshaft position (CKP) sensor and the VVT cam sensor to identify which cylinder is misfiring. When cylinder-2 misfire counts exceed approximately 1.5 percent of crankshaft revolutions (emission threshold, over 1000 revolutions) or 77 or more misfires per 200 revolutions (catalyst-damage threshold), the code sets. The emission-level fault uses two-trip detection before the MIL illuminates steady; the catalyst-damage level triggers an immediate MIL flash on the first detection. At engine speeds above approximately 1900 rpm with light load, the ECM intentionally suppresses individual cylinder misfire codes and stores only P0300.
Symptoms
- MIL illuminated steady (emission-level misfire) or MIL flashing when the catalyst-damage threshold is exceeded
- Rough idle or rhythmic stumble at low rpm, most noticeable when cylinder 2 fires
- Hesitation or power loss under acceleration, especially at the rpm and engine load stored in freeze frame
- Fuel smell or increased unburned hydrocarbon content from exhaust
- Cold-start rough running that may clear once coolant temperature exceeds 75 degrees C (167 F), if freeze-frame ECT was below that threshold
Common causes
- Worn or fouled spark plug on cylinder 2 -- the most frequent root cause; inspect electrode gap, oil fouling, and carbon deposits
- Failed coil-on-plug ignition coil for cylinder 2 -- a failed coil produces zero spark on that cylinder
- Clogged or electrically failed fuel injector on cylinder 2 -- a stuck-closed injector starves the cylinder of fuel
- Low cylinder compression from worn piston rings, burned exhaust valve, or head gasket breach
- Vacuum leak at the PCV hose, intake manifold, or individual runner -- causes lean misfire that may concentrate on one cylinder
- Mass air flow (MAF) sensor fault -- an incorrect air-mass reading causes incorrect fuel delivery across all cylinders
- Valve timing error from a stuck OCV or stretched timing chain -- VVT-related misfires appear at specific rpm and load combinations
Severity & driving advice
Severity: high — Flashing MIL = catalyst-damage rate reached; stop driving promptly. Steady MIL: repair within 1-2 days to prevent converter damage.
Can I drive? Stop if MIL flashing. Steady MIL: repair within 1-2 days.
Diagnostic approach
Make & model notes
:
:
FAQ
Why is the check engine light flashing for P0302?
A flashing MIL means the misfire rate on cylinder 2 has reached the catalyst-damage threshold -- approximately 77 or more misfires per 200 crankshaft revolutions. The ECM flashes immediately on the first detection trip. Stop driving and repair the cause promptly to avoid irreversible catalytic converter damage.
Can swapping the ignition coil diagnose P0302?
Yes. Swap the cylinder-2 coil to another cylinder and clear the code. If the misfire follows the coil to the new location, the coil is faulty. If P0302 remains on cylinder 2, the coil is not the cause and the next suspect is the spark plug or fuel injector.
Does P0302 require a compression test?
Only if spark plug, coil, and injector tests are all normal. A compression test is the appropriate next step when ignition and fuel delivery checks on cylinder 2 are within specification but the misfire persists.
Can low fuel in the tank cause P0302?
Momentarily yes. When the fuel level is very low, the fuel pump can ingest air, causing brief fuel starvation and a misfire. Toyota factory documentation specifically lists insufficient fuel volume as a cause when the fault cannot be reproduced in the shop.