P0305
Fix within a few daysCylinder 5 Misfire Detected. This means your engine's computer has detected that cylinder #5 is not firing correctly or as expected.
Code P0305 means Cylinder 5 Misfire Detected. Common causes: Ignition coil (45%), 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 P0305?
Limit driving, fix within a few days
Essential trips under 10 miles, avoid highways and heavy acceleration. If the CEL is flashing, stop driving immediately.
Stop driving immediately if: Flashing CEL, loud knocking noises, burning smell, rotten egg smell from exhaust, significant power loss
Symptoms of P0305
- 1Engine runs rough, especially at idle
- 2Loss of engine power
- 3Engine hesitates or stumbles during acceleration
- 4Check Engine Light is on, possibly flashing
- 5Reduced fuel economy
- 6Engine shaking or vibrating
Common Causes of P0305
Parts most likely causing this code, ranked by probability
A faulty ignition coil on cylinder 5 fails to provide the necessary spark to ignite the fuel-air mixture.
45% of P0305 cases are fixed by replacing this part
A worn, fouled, or damaged spark plug in cylinder 5 cannot create a strong enough spark for proper combustion.
30% of P0305 cases are fixed by replacing this part
A clogged or malfunctioning fuel injector on cylinder 5 fails to deliver the correct amount of fuel, leading to a misfire.
15% of P0305 cases are fixed by replacing this part
An air leak near cylinder 5's intake path introduces unmetered air, disrupting the fuel-air ratio and causing a misfire.
5% of P0305 cases are fixed by addressing this issue
Problems like worn piston rings, burnt valves, or a blown head gasket in cylinder 5 prevent proper compression, leading to a misfire.
5% of P0305 cases are fixed by repairing this issue
Check These First (Before Buying Parts)
- Listen for any hissing sounds around the engine, which could indicate a vacuum leak.
- Visually inspect the spark plug wire (if applicable) and the ignition coil for cylinder 5 for any cracks, fraying, or burn marks.
- Check the electrical connector to the ignition coil and fuel injector on cylinder 5 to ensure it's securely seated and free of corrosion.
How to Diagnose P0305
- 1Check for a flashing Check Engine Light. A flashing light indicates an active, severe misfire.
- 2Visually inspect the ignition coil and spark plug on cylinder 5 for any obvious damage or signs of wear.
- 3Swap the ignition coil from cylinder 5 with a coil from a different cylinder (e.g., cylinder 1). Clear the code and drive the vehicle. If the misfire moves to the new cylinder (e.g., P0301), the coil is bad.
- 4If the misfire stays on cylinder 5 after swapping coils, swap the spark plug from cylinder 5 with a plug from another cylinder. Clear the code and drive. If the misfire moves, the spark plug is bad.
- 5If the misfire remains on cylinder 5 after swapping both coil and plug, test the fuel injector for cylinder 5. You can swap it with another injector to see if the misfire moves, or test its electrical signal and spray pattern.
- 6Perform a compression test on cylinder 5 to check for internal engine mechanical issues. Compare results to other cylinders and manufacturer specifications.
P0305 on Popular Vehicles
Toyota Camry
2007-2024P0305 on Toyota Camry models is frequently caused by a failing ignition coil or a worn spark plug. It's a straightforward diagnosis for these vehicles.
70% fixed by replacing ignition coil or spark plug
Honda Accord
2003-2024Honda Accord P0305 codes are often traced back to a faulty ignition coil or a clogged fuel injector. Regular spark plug replacement is important to prevent these issues.
60% fixed by replacing ignition coil or fuel injector
Ford F-150
2004-2024For Ford F-150s, particularly the 5.4L Triton engine, P0305 is a very common code. It's almost always an ignition coil or spark plug. Be aware that spark plugs can be difficult to remove and may break in the cylinder head.
80% fixed by replacing ignition coil or spark plug
Frequently Asked Questions
What does P0305 mean?
P0305 indicates that your engine's computer has detected a misfire specifically in cylinder #5. This means cylinder #5 is not contributing power to the engine as it should.
Can I drive with P0305?
Limit driving, fix within a few days. If the Check Engine Light is flashing, stop driving immediately. A flashing light means severe misfires are occurring, which can quickly damage your catalytic converter. If the light is solid, you can drive for short, essential trips, but avoid high speeds or heavy loads.
Will P0305 clear itself?
No, P0305 will not clear itself. The underlying issue causing the misfire must be diagnosed and repaired. Once the repair is made, you will need to clear the code with an OBD-II scanner, or it will clear after several drive cycles if the problem is resolved.
How do I fix P0305 myself?
Start by inspecting and swapping the ignition coil and spark plug for cylinder 5 with known good ones from another cylinder. If the misfire moves, replace the faulty part. If it stays, investigate the fuel injector for cylinder 5, and then consider a compression test if those don't resolve it.
How much does it cost to fix P0305?
DIY repair costs for P0305 typically range from $50-$200 for a new spark plug or ignition coil. Professional repair at a shop will cost $150-$500, depending on labor rates and the specific part needing replacement.
P0305 keeps coming back - why?
P0305 keeps coming back because the root cause was not correctly identified or fully resolved. This often happens if you only replaced a spark plug when the ignition coil was also weak, or if there's an underlying issue like a faulty fuel injector or low engine compression that was overlooked.
Will P0305 fail emissions/smog test?
Yes, P0305 will cause your vehicle to fail an emissions or smog test. A misfire directly impacts exhaust emissions, and the active Check Engine Light will prevent the vehicle from passing inspection.
What's the difference between P0305 and P0300?
P0305 indicates a misfire specifically in cylinder #5. P0300, on the other hand, means 'Random/Multiple Cylinder Misfire Detected,' indicating that misfires are occurring across multiple cylinders or are not consistently tied to a single cylinder.
P0305 on Ford F-150
On Ford F-150s, especially those with the 5.4L Triton engine, P0305 is very common and often points to a faulty ignition coil or spark plug. These engines are known for spark plug issues, including plugs breaking during removal, so use caution and proper tools.
Questions to Ask Your Mechanic
Did you perform a coil swap and spark plug swap to confirm the misfire source?
Good answer: Yes, we swapped the coil and plug from cylinder 5 to cylinder 1. The misfire stayed on cylinder 5, so we then checked the fuel injector and compression.
What were the compression test results for cylinder 5 compared to the others?
Good answer: Cylinder 5 had 180 PSI, which is consistent with the other cylinders. This rules out a major mechanical issue.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
0.5-2 hours
Intermediate - requires an OBD-II scanner and basic hand tools. Swapping coils and plugs is manageable, but diagnosing fuel injectors or compression issues requires more specific knowledge and tools.
Cost of Waiting
Ignoring P0305, especially with a flashing Check Engine Light, sends unburned fuel into your exhaust system. This quickly overheats and destroys your catalytic converter, turning a $50 spark plug or $100 coil job into a $1,200-$2,500 converter replacement.
While You're In There...
If your vehicle uses spark plug wires, they often wear out at a similar rate to spark plugs and coils. Replacing them during the same job prevents future misfires and saves on labor.
These rubber boots protect the coil and ensure a good connection to the spark plug. They can degrade over time, causing misfires, and are easy to replace when the coil is already out.
A clogged PCV valve can sometimes contribute to oil consumption and spark plug fouling, which can lead to misfires. It's a low-cost part and often easy to access.
Tools You'll Need
- OBD-II Scanner
- Socket wrench set
- Spark plug socket (specific size for your vehicle)
- Spark plug gap tool
- Torque wrench
- Dielectric grease
- Anti-seize compound (for spark plugs)
- Multimeter (for testing coils/injectors)
- Compression tester (for advanced diagnosis)
P0305 is a very common misfire code. Most repairs are straightforward, involving a spark plug or ignition coil, and your engine will run smoothly again once fixed.
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Your Next Steps
Step 1: Use an OBD-II scanner to confirm P0305 is the only code. Note if the Check Engine Light is flashing.
Step 2: Visually inspect the ignition coil and spark plug for cylinder 5. Then, swap the ignition coil from cylinder 5 with a coil from a different cylinder. Clear the code and drive. If the misfire moves (e.g., P0301), replace the ignition coil.
Step 3: If the misfire stays on cylinder 5 after swapping coils, swap the spark plug from cylinder 5 with a plug from another cylinder. Clear the code and drive. If the misfire moves, replace the spark plug.