Code will set if Codes 21 and 22 are not set, engine is at normal operating temperature, oxygen sensor voltage is constant within a specified range (.35-.55 volt), throttle angle is greater than idle, a precalibrated amount of time has elapsed since start-up and all conditions have existed for a precalibrated amount of time. Most likely causes of code are: open sensor signal (high) circuit, faulty PCM connection, faulty PCM, faulty oxygen sensor connection or faulty oxygen sensor.

NOTE: Test numbers refer to numbers on diagnostic chart.

This tests if problem still exists. Vehicle cannot enter "closed loop" mode if oxygen sensor circuit is open. Code indicates an open in O2 sensor circuit (steady .35-.55 volt).
Determines if oxygen sensor, wiring or control module is at fault. If wiring is good, grounding oxygen sensor wire will cause .45 volt reference supplied by control module to pull low.
This tests oxygen sensor circuit wiring. Use only a high impedance (10-megohm minimum) digital voltmeter.

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.

Safety Warning

Code 13: Open Oxygen Sensor Circuit: Notes

Use the Manual With the Right Hardware

When to See a Mechanic

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