Diagnostic trouble code (DTC) information ECM-2120

Condition 

Fig 1: Identifying Front Heated Oxygen Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

This diagnostic trouble code (DTC) is stored if the engine control module (ECM) registers a short-circuit to ground or supply voltage or an open-circuit in the circuit for the front probe control.

The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on.

Substitute Value 

• The fuel trim is shut off.

Possible Source 

Signal too high 

• Short-circuit to supply voltage in the signal cable
• Short-circuit to ground in the signal cable
• Damaged heated oxygen sensor (HO2S) or probe control circuit.

Signal too low 

• Open-circuit in the signal cable
• Damaged heated oxygen sensor (HO2S) or probe control circuit.

Fault symptom[s] 

• Malfunction indicator lamp (MIL) lit.