Test Description

The numbers below refer to the step numbers in the diagnostic procedures.

1. 2
   
   After the ignition is turned ON, the HO2S heater heats up causing the HO2S signal voltage to either increase or decrease. This indicates that the HO2S heater is okay.
2. 3
   
   If the HO2S voltage is varying outside the specified range, the condition is not present.
3. 6
   
   If the voltage is below the specified value, the high signal circuit, the low reference circuit, and the PCM are okay.
4. 13
   
   All sensors must be disconnected to isolate a short to ground in the HO2S ignition 1 voltage circuit.
5. 15
   
   Resistance within the specified range indicates the HO2S heater is okay.