Diagnostic Trouble Code (DTC) Information ECM-951C

Condition 

Fig 1: Identifying Atmospheric Pressure Sensor

Courtesy of VOLVO CARS CORPORATION

To warm up the catalytic converter at cold-start the Engine Control Module (ECM) controls idle so that the engine runs at a higher idle rpm until the catalytic converter has reached its operating temperature. If Engine Control Module (ECM) registers that the actual idle rpm (actual value) is over the limit value for a certain time, the diagnostic trouble code (DTC) is generated.

Substitute Value 

• None.

Possible Source 

• Air leakage in the intake system.

Fault symptom[s] 

• Malfunction indicator light (MIL), on
• High idle speed
• Uneven idle