Engine Misfire Detected
Engine misfire is detected by the computer.
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What it means (plain English)
The engine is not firing correctly in one or more cylinders. This can lead to poor performance, increased emissions, and potential damage if not fixed.
What the computer is actually seeing
The engine control module (ECM) monitors the crankshaft position sensor and cylinder head pressure. If it notes a significant deviation or a lack of expected pressure while the engine runs, it triggers a misfire code.
What a healthy reading looks like
Crankshaft position sensor signal should be a steady 0-5V with less than 5% fluctuation. Cylinder pressure should be within 80-120 psi during the compression stroke.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check for any obvious wiring issues or loose connectors related to the crankshaft position sensor. Repair as necessary.
- 22. Inspect spark plugs and fuel injectors; replace if damaged or clogged. Use a multimeter to check if the injectors are receiving the correct voltage.
- 33. Perform a compression test on each cylinder; values should be 80-120 psi. If one cylinder is significantly lower, further investigation is needed (valve issues, head gasket, etc.).
- 44. Check the fuel filter for restriction. Replace if necessary and ensure proper fuel flow.
- 55. Clear the code and take a test drive. If the code returns, further diagnosis on the ECM or cylinder head pressure might be needed.
Common causes
- Faulty spark plug or injector
- Clogged fuel filter
- Low compression in one or more cylinders
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving with a misfire can cause serious engine damage and increased emissions.
Will this code come back after clearing?
Yes, if the underlying issue isn't fixed, the code will likely return.
Why does this code sometimes pair with SPN 3206?
SPN 3206 indicates a fuel system issue that can contribute to misfires when the fuel delivery is inadequate.
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