so i have a ''''99 ml320. the check engine lights goes on and off sometimes. checked the vehicle for codes. got back a PO173 code. can someone elaborate as to what possible cause(s) that may be? i checked under the hood to see if anything was out of the ordinary. i found out that my passenger side valve cover gasket is leaking. might that set off the code?

 

Almost always the air mass sensor.

Replace or try to clean.

 

I concur with air mass meter also change air filter and clean airbox small minute sand particles contaminate the air mass which for everyones infor the $90.00 insert is available instead of buying the whole $500 unit