OBD-II Code P0302 — What It Means & How to Fix It

What Does This Error Mean?

P0302 means your engine's cylinder number 2 is misfiring. This code tells you exactly which cylinder has the problem. A misfire means the fuel in that cylinder is not burning properly. You will likely feel the engine shaking, especially at idle. If the check engine light is flashing, the misfire is severe and you should stop driving.

Affected Models

All vehicles 1996+
Common in Honda Civic and CR-V
Common in Toyota Camry
Common in Ford Focus and Fusion
Common in Chevrolet Equinox

Common Causes

Worn or fouled spark plug in cylinder 2
Failed ignition coil or spark plug wire for cylinder 2
Clogged or dead fuel injector on cylinder 2
Vacuum leak near the cylinder 2 intake port
Low compression in cylinder 2 due to a worn valve or piston ring

How to Fix It

Remove and inspect the spark plug from cylinder 2. Look for heavy black deposits, a worn gap, or cracked porcelain. Replace it with the correct type from your owner's manual.

Cylinder 2 is the second cylinder in the firing order. Check your manual for its location on your specific engine.
Swap the ignition coil from cylinder 2 with the coil from cylinder 3. Clear the code and drive. If the misfire moves to cylinder 3 (P0303), the coil is bad. Replace it.

This swap test costs nothing and is the fastest way to confirm a bad coil.
Check the spark plug wire or coil connector for damage. Look for corrosion, cracks, or melted insulation. Replace any damaged components.

Moisture getting into the spark plug well is a common cause of misfires, especially in rainy weather.
If ignition components are fine, check the fuel injector on cylinder 2. Listen with a long screwdriver or stethoscope for a clicking sound. No clicking means the injector may be dead.

You can also swap the injector from cylinder 2 with another cylinder to test it, just like the coil swap.
If all external components check out, have a compression test done on cylinder 2. Low compression indicates internal engine wear that requires professional repair.

Healthy compression is typically 120 to 180 PSI. All cylinders should read within 10 percent of each other.

When to Call a Professional

If replacing the spark plug and swapping the coil does not fix the misfire, internal engine issues may be the cause. A compression test ($50 to $100) can reveal problems like a leaking valve or blown head gasket. Head gasket repair costs $1,000 to $2,500. Valve work ranges from $500 to $1,500. Do not ignore a persistent misfire — it can destroy the catalytic converter.

Frequently Asked Questions

Is P0302 the same fix as P0301?

The diagnostic process is identical — only the cylinder number changes. P0301 targets cylinder 1 and P0302 targets cylinder 2. The same types of parts can fail: spark plug, coil, injector, or internal engine issue. Just make sure you are working on the correct cylinder.

Can a P0302 misfire damage my catalytic converter?

Yes, unburned fuel from a misfiring cylinder flows into the catalytic converter. This raw fuel can overheat and melt the catalyst material inside. A flashing check engine light means damage is actively happening. Catalytic converter replacement costs $1,000 to $2,500, so fix the misfire quickly.

My car has P0300 and P0302 at the same time. What do I fix first?

Fix cylinder 2 first since P0302 specifically identifies it as the problem. P0300 means random misfires are happening, which could be caused by the cylinder 2 issue. Once you fix cylinder 2, the P0300 code may also go away. If P0300 persists after fixing cylinder 2, there may be additional problems to address.