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.
Short Term FT
The Short Term FT represents a short term correction to fuel delivery by PCM/ECM in response to amount of time oxygen sensor voltage spends above or below the 450 mv threshold. If oxygen sensor has primarily been below 450 mv, indicating a lean air/fuel mixture, short term fuel trim will increase to signal PCM/ECM to add fuel. If oxygen sensor voltage stays mainly above threshold, PCM/ECM will reduce fuel delivery to compenate for indicated rich condition.
Use the Manual With the Right Hardware
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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.