My wife just bought an 09 ML320 Bluetec with low miles and the engine light came on this morning. Any obvious places to look first? Thanks

 

i have seen alot of diesels with issues with the adblue components corroding and some or all components need replacement. also I had one that needed a switching valve replaced under the turbo. but as already stated could really be anything.

 

Code reader might narrow it down a little.

 

Dealership diagnosed the problem as a NOX sensor and adblue level sensor. They said the adblue is a stored code. Will know more today.
Thanks all.