I have a 2001 CLK 320 with three different error codes. PO173 Fuel Trim Malfunction (Bank 2), PO170 Fuel Trim Malfunction (Bank 1), and PO100 MAF or VAF Circuit Malfunction. The Check Engine Light had already been on. I have not had this vehicle too long, so these codes are another language for me. Any help is appreciated.

 

A faulty Mass Air Flow Sensor would cause all those codes to come on..

 

Thanks for the reply. After my original post, I saw the search tab and found in most cases these errors are related to that sensor. As mentioned and described in this forum, I tried the tip for cleaning and that did not work. I called the local auto parts store, and am shocked at the cost for a replacement. Before purchasing the part is if there is any means of testing the sensor to confirm it is defective? I have roughly sixty thousand miles, so maybe it is due for replacement anyway. I am also wondering if the service light will automatically reset and go off when the new sensor is replaced, or do I need to disconnect the battery to make this reset.

Jeff

 

For anyone else with this issue, I replaced the Mass Airflow Sensor and that took care of the problem.

 

i had the codes p0170 and p0173 and was able to pull the mas out . remove the cencor from housing, and cleaned with no residue spray cleaner. you have to reset the codes . if repair un-sucessfull lite will come back in 24 miles. replacing mas wiyh after market is not recomanded.

 

I am now on my third replacement MAS. The first one lasted roughly ten weeks, and the second failed after four weeks. I made sure the MAS I purchased from NAPA was a Bosch, to assure quality. I am hoping the third one is a charm, and fortunatly due to the cost they have been replaced under warranty. Anyone else had this type of failure?

 

I have those 2 codes showing too. The mechanic said its the same air mass thing causing it.