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.
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HOMESERVICE MANUALSCHEVROLET1998CHEVY VAN G2500, VAN CARGO, 5.0 MREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - 5.0LDIAGNOSTIC TROUBLE CODESDTC P0140 - HO2S INSUFFICIENT ACTIVITY BANK 1, SENSOR 2DIAGNOSTIC PROCEDURES
1998 Chevrolet Chevy Van G2500, Van Cargo, 5.0 M
Diagnostic Procedures
1998 Chevrolet Chevy Van G2500, Van Cargo, 5.0 MSECTION Diagnostic Procedures
- Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
- Connect scan tool. Warm engine to normal operating temperature. Run engine at greater than 1200 RPM for 2 minutes. If scan tool indicates closed loop, go to step 5). If scan tool does not indicate closed loop, go to next step.
- Turn ignition off. Disconnect HO2S harness connector. Connect jumper wires between ground, and HO2S ground and HO2S signal circuits of HO2S connector (VCM side). Turn ignition on, with engine off. Monitor HO2S voltage using scan tool. If HO2S voltage is less than .2 volt (200 mV), go to next step. If HO2S voltage is not less than .2 volt (200 mV), go to step 6).
- Turn ignition off. Remove jumper wire. Using DVOM, check voltage between HO2S low circuit and battery positive voltage. If battery voltage is present, go to step 7). If battery voltage is not present, go to step 9).
- DTC is intermittent. Check is additional DTCs are set. Diagnose affected DTC(s). If additional DTCs are not set, see DIAGNOSTIC AIDS.
- Check for open in HO2S signal circuit. If circuit is open, go to step 11). If circuit is okay, go to step 8).
- Check for poor connection at HO2S connector. If connection is faulty, go to step 11). If connection is okay, go to step 10).
- Check for poor connection at VCM connector. If connection is not okay, go to step 11). If connection is okay, go to step 12).
- Repair open in HO2S ground circuit. After repairs, go to step 13).
- Replace HO2S. After replacing sensor, go to step 13).
- Repair circuit as necessary. After repairs, go to step 13).
- Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
- Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
- Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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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.