P0307
Fix within a few daysThe engine's computer detected that cylinder #7 is not firing correctly or is not contributing enough power to the engine.
Code P0307 means cylinder 7 is misfiring. Common causes: Ignition coil (40%), spark plug (30%), fuel injector (15%). Drivability: Limit driving, fix within a few days. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0307?
Limit driving, fix within a few days
Essential trips under 10 miles, avoid highways and heavy acceleration. Do not drive if the Check Engine Light is flashing.
Stop driving immediately if: Flashing Check Engine Light, loud knocking noises from the engine, strong burning smell, rotten egg smell from exhaust, significant power loss.
Symptoms of P0307
- 1Engine runs rough, especially at idle
- 2Noticeable loss of engine power
- 3Engine hesitates or stumbles during acceleration
- 4Reduced fuel economy
- 5Check Engine Light is on, may flash during severe misfire
- 6Strong smell of raw fuel from the exhaust
Common Causes of P0307
Parts most likely causing this code, ranked by probability
A faulty ignition coil fails to provide sufficient spark to ignite the fuel-air mixture in cylinder #7.
40% of P0307 cases are fixed by replacing this part
A worn, fouled, or damaged spark plug in cylinder #7 cannot create a strong enough spark for proper combustion.
30% of P0307 cases are fixed by replacing this part
A clogged or faulty fuel injector for cylinder #7 prevents the correct amount of fuel from entering the cylinder.
15% of P0307 cases are fixed by replacing this part
Low compression in cylinder #7 due to worn piston rings, damaged valves, or a blown head gasket prevents proper combustion.
10% of P0307 cases are fixed by addressing this issue
An air leak near cylinder #7 can cause an incorrect air-fuel mixture, leading to a misfire.
4% of P0307 cases are fixed by repairing this leak
A rare internal fault in the engine's computer can incorrectly trigger a misfire code for cylinder #7.
1% of P0307 cases are fixed by replacing this part
Check These First (Before Buying Parts)
- Check for any other active or pending diagnostic trouble codes (DTCs) with your scan tool.
- Visually inspect the ignition coil and spark plug wire (if applicable) for cylinder #7 for any cracks, burns, or loose connections.
- Listen for any obvious vacuum leaks around the intake manifold near cylinder #7.
How to Diagnose P0307
- 1Check for other related diagnostic trouble codes (DTCs) using a scan tool.
- 2Visually inspect the ignition coil and spark plug for cylinder #7 for any obvious damage or signs of wear.
- 3Swap the ignition coil from cylinder #7 with an adjacent cylinder (e.g., #5 or #6) and see if the misfire code moves to the new cylinder.
- 4If the misfire moves, replace the ignition coil. If it stays, swap the spark plug from cylinder #7 with an adjacent cylinder and recheck.
- 5If the misfire still remains on cylinder #7, test the fuel injector for cylinder #7 (listen with a stethoscope, check resistance, or swap with an adjacent cylinder).
- 6Perform a compression test on cylinder #7 to check for internal engine mechanical issues.
- 7Check for vacuum leaks around the intake manifold near cylinder #7 using a smoke machine or by spraying carb cleaner.
P0307 on Popular Vehicles
Ford F-150
2004-2024P0307 on Ford F-150s with V8 engines is very commonly due to a failing ignition coil or a worn spark plug on cylinder #7. These are high-wear items.
75% fixed by replacing ignition coil or spark plug
Chevrolet Silverado
2007-2024Similar to the F-150, Silverado trucks often experience P0307 due to ignition coil or spark plug failure on cylinder #7. Fuel injectors are also a known, though less frequent, cause.
70% fixed by replacing ignition coil or spark plug
Honda Accord
2003-2024On V6 Honda Accords, P0307 (if cylinder #7 exists, often on the rear bank) can be more challenging due to access. Ignition coils and spark plugs are common culprits, but valve adjustments or carbon buildup can also contribute.
65% fixed by replacing ignition coil or spark plug
Frequently Asked Questions
What does P0307 mean?
P0307 indicates that the engine's computer has detected a misfire in cylinder #7. This means cylinder #7 is not firing correctly or is not contributing its share of power.
Can I drive with P0307?
Yes, for short trips only, but you need to fix it within a few days. If the Check Engine Light is flashing, stop driving immediately. Continued driving with a misfire can cause serious and expensive damage to your catalytic converter.
Will P0307 clear itself?
No, P0307 will not clear itself. A misfire indicates a real problem that requires diagnosis and repair. The code will remain until the underlying issue is fixed and the system monitors complete their cycles without detecting the misfire again.
How do I fix P0307 myself?
Start by inspecting the spark plug and ignition coil for cylinder #7. Swap the coil with an adjacent cylinder to see if the misfire moves. If not, swap the spark plug. If the misfire persists, check the fuel injector for cylinder #7. A compression test can rule out internal engine issues.
How much does it cost to fix P0307?
DIY repair costs range from $20-$100 for a spark plug, $40-$150 for an ignition coil, or $80-$250 for a fuel injector. Professional shop repairs typically cost $150-$500, depending on the part and labor involved.
P0307 keeps coming back - why?
If P0307 keeps returning, it means the root cause was not fully addressed. This often happens if you only replaced one component (like a spark plug) when the actual issue was a different part (like the ignition coil or fuel injector), or a more serious underlying problem like low engine compression.
Will P0307 fail emissions/smog test?
Yes, P0307 will cause your vehicle to fail an emissions or smog test. A misfire means unburned fuel is entering the exhaust, which directly impacts emissions and indicates a problem with the engine's combustion efficiency.
What's the difference between P0307 and P0300?
P0307 specifically indicates a misfire in cylinder #7. P0300, on the other hand, means a 'Random/Multiple Cylinder Misfire Detected,' indicating misfires are occurring in multiple cylinders or are moving between cylinders, making it harder to pinpoint a single faulty component.
P0307 on Ford F-150?
On many Ford F-150 models, especially those with V8 engines, P0307 is frequently caused by a failing ignition coil or a worn spark plug for cylinder #7. These components are common failure points due to heat and mileage. Less often, it can be a fuel injector or an intake manifold gasket leak.
Questions to Ask Your Mechanic
Did you perform a compression test on cylinder #7?
Good answer: Yes, compression on cylinder #7 is [X PSI], which is within specifications compared to the other cylinders.
What were the fuel injector pulse width readings for cylinder #7 compared to others?
Good answer: The pulse width for cylinder #7 was consistent with the other cylinders, indicating the PCM is commanding fuel correctly. We also checked the spray pattern and resistance.
Repair Cost Estimate
DIY Repair
Parts only
$20-$250
Shop Repair
Parts + labor
$150-$600
Save $130-$350 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - Requires basic hand tools, an OBD-II scan tool, and some diagnostic logic. Swapping coils and plugs is manageable for most DIYers, but diagnosing fuel injectors or compression issues requires more specific knowledge and tools.
Cost of Waiting
Continued misfires send unburned fuel into your exhaust system, which rapidly overheats and destroys your catalytic converter. A $50-$150 spark plug or ignition coil job now prevents a $800-$2,500 catalytic converter replacement later.
While You're In There...
If your vehicle uses spark plug wires, they often wear out at the same rate as spark plugs and coils. Replacing them during the same repair prevents repeat labor.
Applying dielectric grease to spark plug boots and coil connections helps prevent moisture intrusion and ensures good electrical contact, extending component life.
Using anti-seize on spark plug threads prevents them from seizing in the cylinder head, making future spark plug changes much easier.
Tools You'll Need
- OBD-II Scan Tool
- Spark Plug Socket (specific size for your vehicle)
- Ratchet and Extensions
- Torque Wrench
- Multimeter (for testing coils/injectors)
- Compression Tester (if needed)
- Fuel Injector Noid Light (optional)
P0307 is a very common engine code, and in most cases, the fix is straightforward and involves replacing a relatively inexpensive part like a spark plug or ignition coil. Your engine will run smoothly again once it's resolved.
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Your Next Steps
Step 1: Use an OBD-II scan tool to confirm P0307 is the only misfire code. Check for any other related codes like P0300 or lean codes (P0171/P0174).
Step 2: Swap the ignition coil from cylinder #7 with an adjacent cylinder. Clear the code and drive the vehicle. If the misfire moves to the new cylinder, replace the ignition coil.
Step 3: If the misfire stays on cylinder #7 after swapping the coil, swap the spark plug from cylinder #7 with an adjacent cylinder. Clear the code and drive. If the misfire moves, replace the spark plug.