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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 102 (Engine Controls - Self-Diagnostics - 3.5L) >> Diagnostic Tests >> DTC P0141: Ho2S Heater Performance (Bank 1; Sensor 2) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition on. Using scan tool, clear DTCs. Observe DTC information for 30 seconds. If DTC P0036 sets, go to DTC P0036: HO2S HEATER CONTROL CIRCUIT (SENSOR 2) . If DTC P0036 is not set, go to next step.
    3. NOTE: HO2S must cool down and ignition must be off for at least 30 minutes before continuing.
  3. Turn ignition on and as quickly as possible, observe and record HO2S 2 voltage. Monitor voltage for 2 minutes and record voltage reading. If HO2S 2 reading increases or decreases from initial voltage reading by at least 150 millivolts, go to next step. If HO2S 2 reading does not increase or decrease from initial voltage reading by at least 150 millivolts, go to step  5.
  4. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions:
    • An intermittent open or high resistance in HO2S high or low signal circuit.
    • An intermittent open or high resistance in HO2S ignition 1 voltage circuit.
    • Poor HO2S or PCM connector terminal contact.
    • Faulty HO2S.

    Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step  15. If no problems are found, see DIAGNOSTIC AIDS .

  5. Turn ignition off. Disconnect the HO2S connector for the sensor that applies to this DTC. Connect a test light between the HO2S ignition 1 voltage circuit and HO2S heater low control circuit terminals on engine harness side. Start engine. Is test light illuminated? If yes, go to next step. If no, go to step  7.
  6. Disconnect test light. Jumper the HO2S low reference circuit terminal to a known-good ground. Jumper the HO2S high signal circuit terminal to a known-good ground. Use scan tool to monitor the HO2S voltage for the sensor that applies to this DTC. Start engine. Is HO2S voltage less than 20 millivolts? If yes, go to step  9. If no, go to step  8.
  7. Connect a test light between HO2S ignition 1 voltage circuit terminal on engine harness side, and a known-good ground. Ensure ignition is ON, with engine OFF. Is test light illuminated? If yes, go to step  10. If no, go to step  11.
  8. Turn ignition off. Remove jumpers from HO2S terminals. Disconnect PCM connector containing the HO2S high and low signal circuits. Using a Digital Multimeter (DMM), measure continuity of HO2S high signal circuit. Next measure continuity of HO2S low signal circuit between PCM connector terminal and HO2S connector terminal, on engine harness side. Is the individual resistance of both circuits less than 5 ohms? If yes, go to step  13. If no, go to step  12.
  9. Replace HO2S. After repairs, go to step  15.
  10. Repair open HO2S heater low control circuit. After repairs, go to  15.
  11. Repair the lack of power on the HO2S ignition 1 voltage feed circuit. If fuse is open, repair short to ground on circuit. An open fuse or lack of power to fuse may cause other DTCs or symptoms to be present. After repairs, go to step  15.
  12. Repair the circuit that measured high resistance. After repairs, go to step  15.
  13. Check for poor connections at PCM connectors. Repair connectors as necessary. After repairs, go to step  15. If connectors are okay, go to next step.
  14. Replace PCM. Program replacement PCM. See PROGRAMMING . After repairs, go to next step.
    15. NOTE: HO2S must cool down and ignition must be off for at least 30 minutes before continuing.
  15. Turn ignition on and as quickly as possible, observe and record HO2S voltage. Monitor voltage for 2 minutes and record voltage reading. If HO2S reading increases or decreases from initial voltage reading by at least 150 millivolts, go to next step. If HO2S reading does not increase or decrease from initial voltage reading by at least 150 millivolts, go to step  2.
  16. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  17. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, system is okay. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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