P0301 P0301 OBD-II: Misfire Detected in Cylinder 1

P0301 Severity Moderate

What P0301 means for you

The code indicates a misfire, which can lead to performance issues and increased emissions.

Symptoms

Flashing Check Engine Light
Engine running roughly
Hesitation or jerking during acceleration
In most situations, drivers may notice no significant issues
Occasionally, there may be performance declines, such as stalling at stop signs or rough idling
Misfires or reduced power, particularly during acceleration
Decreased fuel efficiency

Common causes

The engine control module (PCM) identifies that cylinder one is not adequately contributing to the engine's operation
This leads to the activation of code P0301

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What this code means

The P0301 code signifies that the engine control module has detected a misfire in cylinder one, indicating that this cylinder is not firing as it should. This misfire may result in a variety of performance issues, including rough engine operation and potential decreases in fuel economy.

How a workshop diagnoses it

1. Use an OBD-II scanner to confirm the presence of the P0301 code. 2. Record freeze frame data to understand the conditions under which the code was set. 3. Perform a test drive to replicate the conditions and observe engine load, throttle position, RPM, and road speed. 4. If available, monitor the misfire counter on the scan tool for cylinder-specific data. 5. If no misfire counter is present, consider swapping components like ignition coils or spark plugs to identify the misfire's source.