Join Date: Dec 2016
Vehicle: 1999 ML430, 2000 ML320, 2005 E500 4matic wagon
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
There is only one AIR pump. It is in the center at the top front of the engine. If the P0171 code has not vom back then it is fine.
One or both of the exhaust ports that receive air from the pump is more than likely blocked. It is a know issue with the M112 V6 and M113 V8 engines.