Heated Oxygen Sensor (Ho2S) Diagnostic

The front heated oxygen sensor (HO2S) is a linear type and functions with current control. Therefore, it is not possible to measure the signals from the heated oxygen sensor (HO2S) using a multimeter. The rear heated oxygen sensor (HO2S) is a binary type as with earlier heated oxygen sensors (HO2S). The Engine Control Module (ECM) checks the heated oxygen sensors (HO2S) when the conditions for diagnostics have been fulfilled.

There are two sets of front and rear heated oxygen sensors, one for bank 1 and one for bank 2.

Bank 1; cylinder 1, 2, and 3.

Bank 2; cylinder 4, 5, and 6.

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.