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Home >> Chevrolet >> 2001 >> Cavalier LS, 2.2 4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (Engine Controls Self-Diagnostics - 2.4L) >> 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 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
    2. NOTE: The HO2S must be cool before proceeding with a diagnosis. The ignition must remain OFF for at least one-half hour before proceeding with a diagnosis.
  2. Connect scan tool. Set up scan tool with the proper vehicle identification information prior to turning the ignition ON. Turn ignition on, with engine off. As quickly as possible, observe and record the HO2S voltage for the sensor that applies to this DTC. Monitor the HO2S voltage for two minutes. Does the HO2S voltage increase or decrease from the initial voltage by at least 150 mV? If yes, go to next step. If no, go to step  4 .
  3. The condition that set this DTC is not present. This DTC may have been set by an intermittently open or high resistance HO2S high signal circuit or low signal circuit, an intermittently open or high resistance HO2S heater ignition 1 voltage or a heater ground circuit. A Faulty HO2S or PCM connector terminal contact or a defective HO2S. Repair any of the conditions as necessary. Did you find and correct the condition? If yes, go to step  15 . If no, go to DIAGNOSTIC AIDS  .
  4. Turn ignition off. Disconnect HO2S connector for the sensor that applies to this DTC. Connect a test light between the HO2S heater ignition 1 voltage circuit and ground circuit terminals at the engine harness side. Turn ignition on, with engine off. Does the test light illuminate? If yes, go to next step. If no, go to step  6 .
  5. Disconnect the test light. Jumper the HO2S low signal circuit terminal to a known-good ground. Jumper the HO2S high signal circuit terminal to a known-good ground. Use a scan tool, in order to monitor the HO2S voltage for the sensor that applies to this DTC. Ensure the ignition is ON while the engine is OFF. Is the HO2S voltage less than 20 mV? If yes, go to step  8 . If no, go to step  7 .
  6. Connect the test light between the HO2S heater ignition 1 voltage circuit terminal at the engine harness side and a known-good ground. Ensure the ignition is ON while the engine is OFF. Does the test light illuminate? If yes, go to step  10 . If no, go to step  11 .
  7. Turn ignition off. Remove the jumpers from the PCM connector containing the HO2S high and low signal circuits. Use a Digital Multimeter (DMM) in order to measure the continuity of the HO2S high signal circuit and then the HO2S low signal circuit between the PCM connector terminal and the HO2S connector terminal at the engine harness side. Does the resistance measure less than 5 ohms? If yes, go to step  13 . If no, go to step  12 .
  8. Inspect for poor connections at the harness connector of the HO2S. Did you find and correct the condition? If yes, go to step  15 . If no, go to next step.
  9. Replace HO2S. When complete, go to step  15 .
  10. Repair open in HO2S heater ground circuit. After repairs, go to step  15 .
  11. Repair the lack of voltage on HO2S heater ignition 1 voltage circuit. If fuse is blown, repair short to ground on circuit. A blown fuse or lack of voltage to the 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 proper PCM terminal contact. Repair the connectors as necessary. Did you find and correct the condition? If yes, go to step  15 . If no, go to next step.
  14. Turn ignition off. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  15. Use the scan tool in order to clear the DTCs. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC  . Does the DTC run and pass? If yes, go to next step. If no, go to step  2 .
  16. Using scan tool, observe stored information and Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
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