SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 79 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.4L)DIAGNOSTIC TESTSDTC P0141: HO2S HEATER PERFORMANCE (BANK 1; SENSOR 2)DIAGNOSTIC PROCEDURES
1999 GMC Forward Control 5.7 R, Automatic

Diagnostic Procedures

1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, 2002 Chevrolet Monte Carlo, and 2002 Chevrolet Impala. 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: If engine has just been operating, allow engine to cool until near bias voltage is observed on scan tool before proceeding.
  2. Turn ignition on, with engine off. Monitor HO2S 2 voltage on the scan tool. Does the HO2S 2 voltage go to greater than or less than the previously stabilized voltage, by at least as much as 100 mV within 2 minutes? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
    4. NOTE: Ensure test light is connected to a good ground.
  4. Disconnect the HO2S 2 electrical connector. Turn ignition on, with engine off. Connect a test light between the HO2S 2 heater ignition voltage circuit, in the harness side of the HO2S connector, and ground. Does the test light illuminate? If yes, go to next step. If no, go to step  7.
  5. Turn ignition off. Connect a test light between the HO2S 2 heater ignition voltage circuit, in the harness side of the HO2S connector, and the HO2S 2 heater ground circuit. Turn ignition on, with engine off. Does the test light illuminate? If yes, go to next step. If no, go to step  10.
    6. NOTE: The heater element resistance will vary according to HO2S temperature. A hot HO2S heater element will have a higher resistance than at room temperature.
  6. Turn OFF ignition. Leave HO2S connector disconnected. Allow engine to cool for at least 15 minutes. Measure HO2S 2 heater resistance at HO2S 2 pigtail connector using a Digital Multimeter (DMM). Resistance should be within 2-20 ohms? If yes, go to next step. If no, go to step  11.
  7. Test the HO2S 2 heater ignition voltage circuit for an open fuse. Did you find an open fuse? If yes, go to next step. If no, go to step  9.
  8. Locate and repair the short to ground in the HO2S 2 heater ignition voltage circuit and replace the fuse. After repairs, go to step  13.
  9. Repair the open or high resistance condition in the HO2S 2 heater ignition voltage circuit. After repairs, go to step  13.
  10. Repair the open or high resistance condition in the HO2S 2 heater ground circuit. After repairs, go to step  13.
  11. Before continuing, inspect for poor connections at the HO2S 2 connector. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  12. Replace the HO2S 2. After repairs, go to next step.
  13. 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.
  14. With a scan tool, observe the stored information, 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.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

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.