P0302 on Pontiac: How to Diagnose & Fix
Cylinder 2 Misfire Detected
1 Pontiac model · 1 documented issue · 1 critical · $1,000-$2,500 repair
P0302 on Pontiac by model: symptoms, diagnosis and fix
The first-generation 2.2L Ecotec L61 in 2002-2005 Sunfire (and Cobalt, Cavalier, Saturn Ion) is prone to head gasket failure and cylinder head cracking — particularly if overheated once. Aluminum head warps easily. Often presents as bubbles in coolant reservoir, white smoke, and overheating.
Common Symptoms
- white smoke
- overheating
- bubbles in coolant
- milky oil
- rough idle after warm-up
How to Fix
Pressure-test cooling system to confirm. Head gasket replacement ~$1,000-$1,800 — but ALWAYS have the head pressure-tested and resurfaced (~$150-$250 machine shop) since cracking is so common. If head is cracked, a used head is often the most economical replacement ($200-$400 from yard). Driving while overheating destroys the head; tow it.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Fel-Pro HS 26223 PT-1 cylinder-head gasket set
2002-2005 Pontiac Sunfire 2.2L DOHC Ecotec L61; head bolts are not included and the listing requires TCS46041. Fitment/availability: Fourteen in stock and add-to-cart live at review
- Replacement 698-001 fourteen-piece L61 head-bolt set
2002-2005 Pontiac Sunfire 2.2L DOHC Ecotec L61; includes ten long and four short bolts and interchanges with ES72196/HB32201. Not ES72170.
- Fel-Pro TCS 46041 timing-cover gasket set
2002-2005 Pontiac Sunfire 2.2L L61; verify production details and contents against the removed timing-cover seals.
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P0302 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0302 mean on a Pontiac?
P0302 stands for "Cylinder 2 Misfire Detected." This code means the engine computer has detected a misfire specifically in cylinder 2, meaning that cylinder isn't completing combustion properly on some firing events. The computer watches tiny variations in crankshaft speed to spot when a cylinder fails to fire, and a misfire means the air-fuel mixture isn't igniting correctly — usually from a spark, fuel, or compression problem in that cylinder. You may feel a stumble, rough idle, shaking, loss of power, or a flashing check-engine light, and persistent misfires can damage the catalytic converter. Because it names a single cylinder, the fault is often a component serving just cylinder 2, like its coil, plug, or injector. On Pontiac it is documented across 1 model: Sunfire.
What are the most common causes of P0302?
The most common causes of P0302 are: Worn or fouled spark plug (cylinder 2), Failed ignition coil or coil-on-plug (cylinder 2), Clogged or faulty fuel injector (cylinder 2), Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/bent valve, head gasket), Damaged spark plug wire or boot (if equipped), Carbon-tracked or cracked coil/plug causing spark loss, Faulty PCM/ECM driver (rare). The specific cause varies by vehicle.
How much does it cost to fix P0302 on a Pontiac?
Published repair estimates on Pontiac range from $1,000 to $2,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.