Diagnostic trouble code (DTC) information

Condition 

Fig 1: Identifying Rear Heated Oxygen Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

Diagnostic trouble code (DTC) ECM-2A2A (bank 1) or ECM-2B2A (bank 2) is stored if the control module registers that the resistance of the rear heated oxygen sensor (HO2S) in the pre-heating circuit is too high for a certain amount of time.

Substitute Value 

• None.

Possible Source 

Faulty signal: 

• Contact resistance and oxidation
• Defective rear heated oxygen sensor (HO2S).

Fault symptom[s] 

• The malfunction indicator lamp (MIL) lights.