2018 Envision Stalling and Rough Idle - P0301 Misfire

ClearTheCode admin answer: A P0301 code on your 2018 Buick Envision indicates a misfire detected in cylinder 1. This can lead to rough idling, reduced power, and stalling. It's important to address misfires promptly to prevent potential damage to the catalytic converter.

Here are the most common causes and diagnostic steps:

1. Spark Plug: The spark plug in cylinder 1 could be fouled, worn, or cracked. This is often the simplest and cheapest fix.
2. Ignition Coil: The ignition coil for cylinder 1 might be failing. You can often test this by swapping the coil with a known good cylinder (e.g., cylinder 2) and seeing if the misfire code moves to the new cylinder.
3. Fuel Injector: A clogged or faulty fuel injector for cylinder 1 can prevent proper fuel delivery, causing a misfire. Fuel system cleaners can sometimes help, but a faulty injector may need replacement.
4. Compression Issue: Less common, but a loss of compression in cylinder 1 (due to a bad valve, head gasket, or piston ring) will cause a misfire. This requires more advanced diagnostics.
5. Vacuum Leaks: While less specific to a single cylinder, a significant vacuum leak can affect engine performance and sometimes contribute to misfires.

When to see a shop:

• If swapping spark plugs and coils doesn't resolve the issue or move the code.
• If you suspect a fuel injector problem and don't have the tools to test it.
• If the misfire is accompanied by unusual noises, smoke from the exhaust, or significant power loss.
• A professional can perform a compression test, fuel pressure test, and use advanced scan tools to pinpoint the exact cause of the misfire efficiently.