Diagnostic Trouble Code (DTC) Information ECM-221B

Condition 

Fig 1: Identifying Rear Heated Oxygen Sensor

Courtesy of VOLVO CARS CORPORATION

The engine control module (ECM) monitors the operation of the rear heated oxygen sensor (HO2S) by checking its signal.

The diagnostic trouble code (DTC) is stored if the engine control module (ECM) does not register a signal from the rear heated oxygen sensor (HO2S).

Substitute Value 

• None.

Possible Source 

• Damaged rear heated oxygen sensor (HO2S).

Fault symptom[s] 

• Malfunction indicator lamp (MIL) lit.