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 13: Open O2 Sensor Circuit: Notes
- Code 13 will set if the following conditions occur:
- Engine is at operating temperature.
- At least 40 seconds engine running time after start.
- Oxygen signal steady between .35 and .55 volt.
- Throttle position sensor signal greater than idle.
- All conditions must be met for 30 seconds.
If all the above conditions for a Code 13 exist, system will not go into "closed loop".
- Determines if the sensor or the wiring is the cause of the Code 13.
- When performing this test, use only a high impedance (10-megohm) digital volt/ohmmeter. This test checks the continuity of circuits No. 412 and 413. If circuit No. 413 is open, the ECM voltage on circuit No. 412 will be greater than .6 volt.
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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.
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