Malfunction of the mass air flow sensor on the Mercedes S-class (W221) manifests problems with idle speed, reduced car dynamics, as well as the appearance of the Check Engine indication. To replace the sensor, do the following:
- Turn the ignition off.
- We're taking off the air filter.
- Disconnect from the air flow-meter B5/2 connector 2.
- Open the right-hand tab 3 and the air flow meter at the intake manifold 4.
- Unlock the right tab 3b and pull the sensor back a bit.
- Checking for 7 between the air duct and the airflow sensor 7.
- Check for no damage to the locking tabs as well as the spring plate of the spring plate 5.
- We're changing the defective elements, and we're packing it all back.