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.
Test Step 8 - 1/1 O2 SENSOR
- Ignition on, engine not running.
- Disconnect the 1/1 O2 Sensor harness connector.
- With the scan tool, monitor the 1/1 O2 Sensor voltage.
- O2 Sensor voltage should read between 4.1 and 5.0 Volts on the scan tool with the connector disconnected.
- Connect a jumper wire between the (K41) Signal circuit and the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
The voltage should drop from between 4.1 and 5.0 Volts to 2.5 Volts with the jumper wire in place.
Did the O2 Sensor voltage change from between 4.1 and 5.0 Volts to 2.5 Volts with the jumper wire installed?
Yes
- Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. If OK, replace the O2 Sensor. Refer to Removal and Installation .
- Perform the Powertrain Verification Test. Refer to Engine .
No
Remove the jumper wire before continuing.
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.