I have an intermittent engine indicator light, along with a P0172 rich mixture code. Took it to the dealer for a free inspection, and they are telling me it is caused by a "leaking purge line (from motor to vacuum supply line)". Can anyone please point me to the exact location of this line? I don't want to guess and replace another wrong part . Is it the infamous $12 vacuum hose, or something totally unrelated? I have the M271 engine. Thank-you.

 

The M271 has several vacuum lines on top of the engine which tend to crack after a few years. When my lines failed I got a P0171 (too lean) code. P0172 is too rich. I would start with the vacuum lines.

All the hoses attached to the PCV should've been replaced (the $12 hose and the other pieces along the same line) under recall at some point. Did you check with the dealer to see if it was performed on your car?

 

I was finally was able to get hold of the dealer and check for the vent hose service campaign. Apparently it was already performed several years ago, and MB only covers the repair once. The good news is the engine indicator light has remained off since then, so I will probably leave it alone for now.

Looking at your old thread, I can see the hoses you replaced are just around/below the airbox. But some of the vent hoses referenced in service campaign #2008020002 are under the supercharger as well. So I am still not certain about the exact location of this purge line. There seems to be so many of them on this engine.