Oxygen Sensor: Description and Operation

Heated oxygen sensor (HO2S) diagnostic

Heated oxygen sensor (HO2S) diagnostic
The front heated oxygen sensor is of the linear type and works with current control. Therefore, signals from the heated oxygen sensor cannot be measured with a multimeter.
Centre and rear heated oxygen sensors are voltage-controlling of binary type.
The engine control module (ECM) checks the heated oxygen sensors (HO2S) when the conditions for the diagnostic have been met.

The following faults can be registered by the control module:
- Electrical faults in the circuits for the heated oxygen sensors (HO2S) and for oxygen sensor preheating.
- Adaption The control module checks that the long-term fuel trim is not higher or lower than the pre-defined values.
- Heated oxygen sensor (HO2S) dynamics. The control module checks that the changeover period between rich and lean mixtures is not too long.
For further information about heated oxygen sensor (HO2S) diagnostics, see diagnostic trouble code (DTC) information for the diagnostic trouble codes (DTCs).