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 Procedure
- DP1 CHECK FOR DTCS NOTE: For vehicles with automatic transmission and OSS sensor DTCs, refer to the appropriate Automatic Transmission, Diagnostic Trouble Code (DTC) Charts.
Are DTCs P0500, P0503, P0720, P0721, P0722, P0723, P1500, P1502, P1900, P1934 or P193F present?
Yes No GO to DP2 RETURN to Symptom Charts for further direction. - DP2 VERIFY THE DRIVE CYCLE
- Access the PCM and monitor the OSS_SRC (RPM) PID.
- Access the PCM and monitor the VSS (SPD) PID.
- Drive the vehicle.
- Monitor both of the PIDs in all transmission gear ranges while increasing and decreasing the speed.
Do both PID readings increase and decrease with engine and vehicle speed?
Yes No GO to DP3 GO to DP4. - DP3 VISUAL INSPECTION
- OSS Sensor connector disconnected.
- Inspect the OSS sensor harness for damage.
- Inspect the OSS harness connector for damage and correct seating.
- Carry out a thorough wiggle test on the OSS harness.
Is a concern present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.GO to Pinpoint Test Z. - DP4 CHECK VOLTAGE TO THE OSS SENSOR
- Ignition OFF.
- OSS Sensor connector disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) OSS Sensor Connector, Harness Side (-) Vehicle Battery VBPWR - Pin 1 Negative terminal
Is the voltage greater than 10.5 V?
Yes No GO to DP5 REPAIR the open circuit. Clear the PCM DTCs.
REPEAT the self-test. - DP5 CHECK THE OSS CIRCUIT FOR AN OPEN
- Ignition OFF.
- PCM connector disconnected.
- OSS Sensor connector disconnected.
- Measure the resistance between:
(+) PCM Connector, Harness Side (-) OSS Sensor Connector, Harness Side OSS OSS - Pin 2 SIGRTN SIGRTN - Pin 3
Are the resistances less than 5 ohms?
Yes No GO to DP6 REPAIR the open circuit. Clear the PCM DTCs.
REPEAT the self-test. - DP6 CHECK THE OSS CIRCUIT FOR A SHORT TO GROUND
Is the resistance greater than 10K ohms?
Yes No GO to DP7 REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - DP7 CHECK THE OSS CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- OSS Sensor connector disconnected.
- Measure the voltage between:
(+) OSS Sensor Connector, Harness Side (-) Vehicle Battery OSS - Pin 2 Negative terminal
Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs.
REPEAT the self-test.REMOVE the OSS sensor and INSPECT the target wheel. REPAIR as necessary. If OK, INSTALL a new OSS. REFER to the appropriate Manual Transmission article.
Clear the PCM DTCs. REPEAT the self-test.
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.