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.
Code Enable Criteria
For DTC to run, the following conditions must be met:
- Engine is operating on alternative fuel.
- Engine speed is more than 500 RPM.
- Engine has been operating for at least 2 minutes.
- AF ECU determines O2S has been at operating temperature for at least 2 minutes.
- Engine coolant temperature must be more than 104°F (40°C) and calculated mass air flow must be more than 6 grams per second for 2 minutes for AF ECU to determine O2S is at operating temperature.
DTC will set when AF ECU detects an O2S signal voltage stuck between 0.347 volt and 0.550 volt (in-active) for 9 continuous seconds or AF ECU detects an O2S signal voltage between zero and one volt that has not performed a rich/lean switch for 15 continuous seconds. When DTC is set, AF ECU will operate in open loop fuel control.
NO RELATED
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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.