Diagnostic trouble code (DTC) information ECM-421C

Condition 

Fig 1: Identifying Canister Purge (CP) Valve

Courtesy of VOLVO CARS OF NORTH AMERICA.

The diagnostic trouble code (DTC) is stored if the engine control module (ECM) registers that the signal from the evaporative emission system (EVAP) valve is too high.

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

Substitute Value 

• twin heated oxygen sensor (HO2S) control disabled.

Possible Source 

• Short-circuit to supply voltage in the signal cable
• Damaged evaporative emission system (EVAP) valve.

Fault symptom[s] 

• Malfunction indicator lamp (MIL) lit.