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:
- An improperly installed air cleaner outlet duct.
- The air cleaner outlet duct for a collapsed duct, restrictions, or a missing or plugged air filter.
- Throttle body and intake manifold vacuum leaks.
- A damaged or blocked throttle body inlet.
- Exhaust system for corrosion, leaks, or loose or missing hardware.
- The HO2S is installed securely and the pigtail harness is not contacting the exhaust manifold or wires.
- HO2S contamination.
- The vacuum hoses for splits, kinks, and proper connections.
- Excessive water, alcohol, or other contaminants in the fuel.
- PCM sensor grounds that 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.