Mesh contamination (visual inspection)
Remove the mass air flow sensor. Nets must be free of foreign objects (see picture below).
Do not clean the screens with compressed air or in any other way: this will damage the sensors and cause erroneous CUP readings.
Check the tightness of the air path to the mass air flow sensor: violation
connections or breakdown of the air filter housing and air ducts. the presence of pads.
If necessary, replace the mass air flow sensor and clean the air supply path to it.
Breakdown of electrical components
Remove the mass air flow sensor. There must be no broken electrical components (see picture).
Replace the mass air flow sensor if necessary.
Oxidation of electrical elements
Remove the mass air flow sensor. Electrical components must be free of greenish deposits.
Replace the mass air flow sensor if necessary.
Dirty air flow sensor
Check the consistency of the values during the first 5 seconds after starting the engine.
Coolant temperature: 80°C.
Engine speed: idle (800 min-1).
Measured air flow rate: 59 kg/h±5% (G9T engine) and 47 kg/h±5% (F9Q engine) (given for example).
EGR valve SCR: 5%.
After starting the engine
Coolant temperature: 80°C.
Engine speed: idle (800 min-1).
Measured air flow rate: 33 kg/h±5% (G9T engine) and 27 kg/h±5% (F9Q engine) (given for example).
EGR valve SCR: 35% to 45% or 5%.
See fault DF056 «Mass Air Flow Sensor Circuit» 2. def.
Replace the mass air flow sensor if necessary.