2000 Mercedes Benz MAF sensor

On this page we will illustrate how to diagnose and repair a Mass Airflow Sensor Problem on a 2000 Mercedes Benz C230 related to a computer code P0170.  Because problems related to the Mass Airflow Sensor normally cause either a lean or rich fuel mixture, this type of problem will cause the computer to generate other codes.  In this particular case, this vehicle had the following codes: P0300- A random multiple cylinder misfire, P0301- Cylinder 1 misfire, P0302- Cylinder 2 misfire, P0303- Cylinder 3 misfire, P0304- Cylinder 4 misfire.

It would be easy to misdiagnose the problem that this vehicle had if it didn't have the code P0170 because it would be easy to assume that the problem was either a low fuel pressure or ignition system malfunction.

As you see in the image, the main code that appears on the hand-held scanner screen: P0170- Mass Airflow Sensor failure.  To make sure that the problem was, in fact, a defective Mass Airflow Sensor, we read the data that was being sent to the computer and we noticed that while accelerating, the sensor would stop increasing its signal at 5.5 lbs/min.  At that moment, the mixture would become so lean that the vehicle would hesitate under acceleration and that triggered the other codes.  This particular sensor has a range of 0-20 lbs/min.  Once the sensor was replaced the readings were as follow:  0.5 lbs/min at idle, and 18.5 lbs/min at 4,000 rpm under acceleration.  Below are the steps to replace the sensor.

















Unplug the Mass Airflow Sensor electrical connector.


































Loosen the hose clamps on the Air Intake hose at the Mass Airflow Sensor side and the opposite side near the throttle body housing.
























Remove the Air Intake tube.
























Undo the clamps that secure the Mass Airflow Sensor in place and remove the sensor from the vehicle.

























Compare the new and the old sensor prior to installation.  Install it, clear the code, and take the vehicle for a test drive to ensure it is working properly.