Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, and 2002 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Never solder the HO2S wires.
Inspect for the following conditions:
- Inspect for an improperly installed air cleaner outlet duct.
- Inspect the air cleaner outlet duct for a collapsed duct, restrictions, or a missing or plugged air filter.
- Inspect the throttle body and the intake manifold for vacuum leaks.
- Inspect for a damaged or blocked throttle body inlet.
- Inspect the exhaust system for corrosion, leaks, or loose or missing hardware.
- Verify that the HO2S is installed securely and the pigtail harness is not contacting the exhaust manifold or wires.
- Inspect for any HO2S contamination.
- Inspect the vacuum hoses for splits, kinks, and proper connections.
- Test for excessive water, alcohol, or other contaminants in the fuel.
- Verify that the PCM sensor grounds are clean, tight, and properly positioned.
An intermittent may be caused by any of the following conditions:
- A poor connection
- Rubbed through wire insulation
- A broken wire inside the insulation