Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0300-P0308 Detection Logic
On DTC P0300-P0308, MIL is set in 2 stages. If the ECM detects misfiring, strong enough to cause catalytic converter overheating, for any 200 revolutions of the engine, MIL will blink, but will not stay illuminated. If the ECM detects misfiring, strong enough to cause deterioration of catalytic converter, during 2 consecutive drive cycles, for any 1000 revolutions of the engine, MIL will illuminate.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.