P0301 - Cylinder 1 Misfire Detected
P0301 is a generic powertrain diagnostic trouble code indicating Cylinder 1 Misfire Detected. It relates to the Ignition System / Misfire system.
DTC Breakdown (SAE J2012)
| System | Powertrain (P) |
| Type | Generic |
| Subsystem | Ignition System / Misfire |
| Fault Index | 01 |
| Standard | SAE J2012 / ISO 15031-6 |
What does diagnostic code P0301 mean?
The engine computer has detected a misfire condition specifically localized to cylinder number 1. Combustion is failing in this cylinder.
Severity Level & Driveability Details
Severity: High
Active misfires dump unburned fuel into the exhaust, leading to catalytic converter failure. A flashing check engine light requires immediate attention.
Common Symptoms of P0301
- Active flashing of the check engine light on the instrument cluster.
- Engine shaking or heavy vibration at idle.
- Rough acceleration and lack of power.
- Fuel smell from the tailpipe.
Typical Causes for P0301
- Bad spark plug in cylinder 1.
- Failed ignition coil or spark plug wire for cylinder 1.
- Faulty fuel injector for cylinder 1.
- Low compression in cylinder 1 (burnt valve, broken rings, blown head gasket).
Diagnostic and Troubleshooting Steps
Swap the ignition coil from cylinder 1 to cylinder 2. If the misfire code changes to P0302 on the scanner, the coil is bad. If it stays P0301, swap the spark plug or inspect the injector and cylinder compression.
Typical Repairs and Fixes
- Replacing the cylinder 1 ignition coil or spark plug.
- Replacing the cylinder 1 fuel injector.
- Repairing mechanical engine issues (valves, head gasket).
Sensor Location & Parts Involved
The ignition coil and spark plug for cylinder 1 are located on top of the cylinder head on the engine block.
Clearing Code & Recurrence
Resolve the underlying ignition or fuel fault in cylinder 1, then reset the codes using an OBD2 scanner.
Emissions & Smog Inspection Impact
Misfiring in cylinder 1 releases unburned hydrocarbons into the exhaust stream, potentially damaging the catalytic converter and raising emissions.
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Related Diagnostic Codes
Sources & References
This diagnostic guide is compiled and verified against the following authority sources:
- NHTSA Recall Database
- EPA OBD II Regulations
Frequently Asked Questions about P0301
What does the cylinder 1 misfire code P0301 mean?
The engine control module logged P0301 after detecting a combustion misfire in cylinder 1. This indicates that the fuel-air mixture is failing to ignite properly inside the cylinder 1 chamber.
Is it safe to drive with the cylinder 1 misfire code P0301 active?
No, driving with active misfires in cylinder 1 can ruin the catalytic converter.
How much does it cost to repair a cylinder 1 misfire code P0301 fault?
Replacing an ignition coil or spark plug for cylinder 1 typically costs $100-$300. Replacing the fuel injector for cylinder 1 costs $200-$450.
What are the common causes of the cylinder 1 misfire code P0301?
Trigger conditions for the cylinder 1 misfire code P0301 include: A worn or fouled spark plug in cylinder 1., Failed ignition coil or damaged spark plug wire for cylinder 1., Faulty fuel injector or poor fuel atomization in cylinder 1..
Can I clear the check engine light for cylinder 1 misfire code P0301?
Resolve the underlying ignition or fuel fault in cylinder 1, then reset the codes using an OBD2 scanner.
Will the cylinder 1 misfire code P0301 cause an inspection failure?
Misfiring in cylinder 1 releases unburned hydrocarbons into the exhaust stream, potentially damaging the catalytic converter and raising emissions.