Test Description
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.
The numbers below refer to the step numbers in the diagnostic procedures.
- 2
Allow the engine to cool before performing this test. If the sensor is at the operating temperature, the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-600 mV this indicates the HO2S heater is inoperative. - 3
If more than one HO2S DTC is set, this is a good indication that the HO2S fuse is open. Test all the related circuits going to all the HO2S for a short to ground. If you cannot locate a shorted circuit, you may need to disconnect each HO2S one at a time to locate a shorted sensor. - 4
This step determines if an ignition positive voltage supply is available at the sensor. - 5
This step determines if a ground is available at the sensor. - 6
This step determines if the HO2S heater element is internally open. - 7
Inspect the ignition positive voltage circuits at the underhood electrical center for poor connections. - 8
Test the ground circuits for an open if more then one heater DTC sets.