Diagnostic trouble code (DTC) information ECM-420C

Condition 

Fig 1: Identifying Evaporative Emission System (EVAP) Valve

Courtesy of VOLVO CARS OF NORTH AMERICA.

When the control module activates evaporative emission system (EVAP) control, the idle air trim or short-term fuel trim will change. The diagnostic trouble code (DTC) is stored if the engine control module (ECM) does not detect any change in the idle air trim or the long term fuel trim when evaporative emission (EVAP) control is active. The engine control module (ECM) interprets this as a damaged evaporative emission (EVAP) system.

Substitute Value 

• None.

Possible Source 

• Damaged evaporative emission system (EVAP) valve.

Fault symptom[s] 

• Malfunction indicator lamp (MIL) lit.