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 Oxygen Sensor Circuit: Notes
The O2 sensor is like an open circuit and produces no voltage when it is below about 600°F (316°C). An open sensor circuit or cold sensor causes "open loop" operation.
- Code 13 will set at normal operating temperature if at least 2 minutes have passed since engine start, O2 signal voltage is steady between .35 and .55 volt and throttle position sensor signal is above 7 percent (1200 RPM). All conditions must be met for at least 60 seconds.
- Determines if the O2 sensor, ECM or wiring is at fault.
- Use only a high impedance DVOM for this test. This test checks for continuity in circuits No. 412 and 413. If circuit No. 413 is open, 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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