P0302: Cylinder 2 Misfire Detected (Meaning, Causes, Fixes)
What P0302 means
P0302 is a generic OBD-II code, so it applies to all OBD-II vehicles, though repair steps vary by make and model. RepairPal explains how it's detected: the misfire monitor counts crankshaft sensor pulses, and when cylinder 2 isn't contributing its share (more than about a 2 percent RPM variance between cylinders) it sets P0302 and turns on the check engine light. Above roughly a 10 percent variance the light blinks to warn of a misfire harmful to the catalytic converter. OBD-Codes.com adds that an intermittent or mild misfire may first show as a pending code with the light flashing only while the misfire happens, and that a consistent misfire stores P0302 with a steady light. Cylinder numbering differs between engines, so check your service information to find cylinder 2. The sources disagree on fuel injectors: OBD-Codes.com lists faulty injectors as a possible cause, while RepairPal lists fuel injectors and oxygen sensors among the common misdiagnoses for P0302. RepairPal also adds incorrect ignition timing and MAF, crank/cam and throttle position sensor faults, while OBD-Codes.com specifically calls out an EGR valve stuck wide open or clogged EGR ports.
Severity: can I keep driving?
Stop and fix promptly
RepairPal rates P0302 'Urgent' and OBD-Codes.com classifies it as severe, because the conditions that set it can damage the catalytic converter and the engine. If the check engine light is flashing, a severe misfire is happening right now, so ease off, avoid hard acceleration and get it checked as soon as you safely can.
Common symptoms
- Check engine light on, or flashing while the misfire is happening
- Rough or unstable running at idle or under light acceleration
- Hesitation or jerking when accelerating, and lack of power
- Odd odor from the exhaust (listed by OBD-Codes.com)
- Rough idle, dying at stop signs or lower fuel economy (listed by RepairPal)
- Often no adverse symptoms noticed by the driver (noted by RepairPal)
Likely causes
Roughly most to least common, based on the sources below. Your vehicle may differ.
- Worn or faulty spark plug on cylinder 2
- Defective ignition coil, spark plug wire or boot, or distributor cap and rotor where fitted
- Major vacuum leak
- Fuel delivery problems such as a weak fuel pump, fuel pump relay, clogged fuel filter or low fuel pressure
- Faulty fuel injector (listed by OBD-Codes.com; RepairPal calls injectors a common misdiagnosis)
- EGR problems, such as an EGR valve stuck open or clogged EGR ports
- Incorrect ignition timing or a defective MAF, crankshaft, camshaft or throttle position sensor (listed by RepairPal)
- Mechanical engine problems such as low compression, a leaking head gasket or valve problems
Diagnostic steps you can do
Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.
- Read all stored codes and freeze frame data. OBD-Codes.com says lean, fuel supply and EGR codes should be fixed before diagnosing the misfire, and other misfire codes (P0300, P0301, P0303, P0304) point to a shared cause.
- Visually inspect the cylinder 2 coil, spark plug and boot. OBD-Codes.com says parts contaminated with oil, coolant or water must be cleaned or replaced.
- Inspect the coil's wiring and connector, and listen for a large vacuum leak with the engine running.
- If spark plugs are due by mileage, replacing them all is regular maintenance anyway.
- On coil-on-plug engines, a common check is to swap cylinder 2's coil with a neighboring cylinder, clear the code and see whether the misfire follows the coil.
- Clear the code and take a lengthy test drive to see if it returns, and check for technical service bulletins for your vehicle if it does.
Typical fixes
- Replace the spark plug, boot or wire, or ignition coil on cylinder 2 (OBD-Codes.com recommends replacing the plug and boot along with a failed coil)
- Repair vacuum leaks
- Repair fuel delivery problems or a faulty injector once testing confirms it
- Repair EGR, ignition timing or sensor faults found during diagnosis
- Repair mechanical problems found by a compression or leak-down test
- Replace the catalytic converter if a long-running misfire has damaged it
Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.
🛠 When to call a pro
- The check engine light is flashing
- The misfire stays on cylinder 2 after replacing the plug and coil
- A compression or leak-down test is needed to check valves, rings or the head gasket
- Diagnosis needs the engine running under load in gear, which OBD-Codes.com describes as a two-person job with wheel chocks
Where to buy
Plain search links. Always match parts to your exact year, make, model and engine.
FAQs
Can I drive with P0302?
RepairPal rates it 'Urgent' and OBD-Codes.com calls it severe. If the check engine light is flashing, the misfire can damage the catalytic converter, so limit driving and get it fixed soon.
Is P0302 always a bad spark plug or coil?
No. OBD-Codes.com says ignition defects are the most common cause, but both sources also list vacuum leaks, fuel delivery, EGR faults and mechanical problems. Swapping the coil to another cylinder is a cheap way to see if the misfire follows it.
What's the difference between P0300 and P0302?
P0302 pins the misfire to cylinder 2. P0300 means random or multiple cylinders are misfiring, which usually points to something shared by all cylinders, such as fuel pressure or a vacuum leak.
Sources
Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.