Heated Oxygen Sensor Diagnostics

The front heated oxygen sensor is of the linear type and works with current control. That is why it is not possible to measure the signals from the heated oxygen sensor with a multimeter. Rear heated oxygen sensor is of the binary type and functions as earlier heated oxygen sensors. The engine control module (ECM) checks the heated oxygen sensors when conditions for diagnostics have been fulfilled.

There is a front and a rear heated oxygen sensor.

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).