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 MANUALSCHEVROLET1997CHEVY EXPRESS G3500, VAN CARGO, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 71 (ENGINE CONTROLS - TESTS W/CODES - 5.0L)DIAGNOSTIC TROUBLE CODESDTC P0155 - HO2S HEATER CIRCUIT BANK 2, SENSOR 1DIAGNOSTIC PROCEDURES
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 F
Diagnostic Procedures
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 FSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 1998 GMC Savana, 1998 Chevrolet Chevy Van, and 1998 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
- Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
- Install scan tool. Turn ignition on, with engine off. Monitor HO2S voltage using scan tool. If HO2S voltage gradually decreases by .15 volt (150 mV), go to DIAGNOSTIC AIDS. If HO2S voltage does not gradually decrease by .15 volt (150 mV), go to next step.
- Check HO2S ignition feed circuit fuse. If fuse is open, go to step 12). If fuse is okay, go to next step.
- Turn ignition off. Disconnect HO2S connector. Using test light, probe HO2S connector terminal "D" (engine harness side) to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
- Connect test light between terminals "C" and "D" of HO2S connector (engine harness side). If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
- Allow HO2S to cool for about 10 minutes. Using DVOM, check resistance between HO2S ignition feed and heater ground circuit at HO2S pigtail. If resistance is 3-10 ohms, go to step 9). If resistance is not 3-10 ohms, go to step 11).
- Repair open in HO2S ignition feed circuit. After repairs, go to step 14).
- Repair open in HO2S heater ground circuit. After repairs, go to step 14).
- Repair for poor connection at HO2S harness terminals. Repair as necessary. After repairs, go to step 14). If connection is okay, go to next step.
- Turn ignition off. Disconnect VCM harness connector. Check resistance between HO2S signal and low circuits. If resistance is greater than 5 ohms, go to step 13). If resistance is not greater than 5 ohms, go to next step.
- Replace HO2S. After replacing sensor, go to step 14).
- Repair short to ground in battery feed circuit. Replace fuse. After repairs, go to step 14).
- Repair open or poor connection in HO2S signal circuit or low circuit. After repairs, go to next step.
- Allow engine to cool down for about 30 minutes. Turn ignition on, engine off. Using scan tool, select DTC, CLEAR INFO function. Monitor HO2S reading on scan tool. If displayed voltage gradually decreases by 150 mV, go to next step. If displayed voltage does not gradually decrease by 150 mV, repeat step 3).
- Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test. If not additional DTCs are set, system is okay.
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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.