2018 GMC P0301: What It Means & Is It Safe to Drive?
P0301 on the 2018 GMC: Cylinder 1 Misfire Detected. Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
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What this code means
The PCM has detected a misfire specifically on cylinder 1. Similar to P0300, but pinned to a single cylinder.
Common causes on the 2018 GMC
- Worn or fouled spark plug on cylinder 1
- Failing ignition coil or coil-on-plug
- Leaking or clogged fuel injector
- Low compression in cylinder 1
Symptoms
- Check Engine Light (often flashing when misfire is severe)
- Rough idle or shaking, especially at low RPM
- Loss of power under load
Typical fixes
- Replace spark plug and/or coil on cylinder 1
- Test and clean or replace the injector
- Perform compression test and repair internal issues if needed
Repair cost range
For a 2018 GMC, repairs for P0301 typically fall between $150 and $900, depending on the root cause and labor rates in your area.
Known issues on GMC
GMC Sierra 5.3L AFM P0301 should prompt an AFM lifter inspection before coil diagnosis—cylinder 1 is a deactivation cylinder. On the 2.4L Ecotec Terrain, P0301 can come from a timing chain stretch causing incorrect cam timing. On the 3.6L DI Acadia, carbon buildup on intake valves is the likely cause.
Most commonly affected models
Sierra 5.3L AFM 2007–2014Terrain 2.4L Ecotec 2010–2017Acadia 3.6L DI 2007–2016