Test Description

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

1. 2
   
   After the HO2S heater is commanded 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 test lamp illuminates, the low reference circuit between the HO2S and PCM terminal C1-63 is okay and the PCM low reference terminal is okay.
4. 7
   
   If the voltage is below the specified value, the high signal circuit, the low reference circuit, and the PCM are okay.
5. 11
   
   The opposite bank HO2S must be disconnected to isolate a short to ground in the HO2S heater high control circuit.
6. 15
   
   Resistance within the specified range indicates the HO2S heater is okay.