Checking the flame sensor

Check that the flame sensor is not clogged with soot.

Remedy as necessary.

Other information: 

• For cars manufactured up to w38 2001 inclusive, see Overheat protection thermostat / flame sensor / engine coolant temperature sensor, replacing
• For cars manufactured from w39 2001 inclusive, see Replacing the overheat protection thermostat, the flame sensor and the engine coolant temperature sensor .

Fig 1: Identifying Flame Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

Was a fault detected? 

• YES 

  Refer to Verification 

• NO 

  Refer to Checking components and wiring