P0301
Cylinder 1 Misfire Detected
Severeignition
Overview
The P0301 code means the PCM has detected a cylinder 1 misfire detected condition. This diagnostic trouble code relates to the ignition system, which is critical for proper combustion in the engine cylinders. When this code is triggered, one or more cylinders may not be firing correctly, leading to rough running, power loss, and potential catalytic converter damage if not addressed.
Symptoms
- Noticeable engine vibration
- Difficulty starting the vehicle
- Exhaust smell of unburnt fuel
- Flashing Check Engine Light during acceleration
Common Causes
- Failed ignition control module
- EGR valve malfunction
- Low fuel pressure
- Faulty crankshaft or camshaft position sensor
Diagnosis Steps
- 1Connect an OBD-II scanner and read all stored trouble codes and freeze frame data
- 2Inspect spark plugs for wear, fouling, or damage; replace if necessary
- 3Test ignition coils using a multimeter or ignition coil tester
- 4Check spark plug wires and boots for damage or arcing
- 5Perform a compression test on the affected cylinder(s)
Estimated Repair Cost
$100 — $500
Cost varies by vehicle, location, and repair shop. Includes parts and labor.
Commonly Affected Vehicles
Hyundai ElantraNissan SentraChevrolet EquinoxSubaru Forester
Related Codes
More Ignition Codes
Frequently Asked Questions
Driving with a misfire is not recommended. A misfiring engine can damage the catalytic converter, reduce fuel economy, and lead to complete engine failure. If the Check Engine Light is flashing, stop driving immediately.