Diagnosing Fault : Merc W203.

MarkeR · 9 Jun 2016 at 14:45

Hi All

I am presuming that the fault when it appears is a Lambda sensor fault.

I have a OBD bluetooth reader and the Fuel System is atating that there is an intermittent fault with the O2 sensor. I presume this is one of the lambda sensors going.

I recently replaced the MAF as I was getting a CEL error with that as well.

Can anyone confirm.

thanks

Six6siX · 9 Jun 2016 at 14:49

What specific error code(s) do you get with the reader?

STAR would be the quickest method to track it down if you had access to that but something like this should be traceable easily enough without.

MarkeR · 9 Jun 2016 at 14:52

Cant remember the code off hand, but it states System Too Lean on the CEl, then when I go into the fuel diagnostics, that is where I ssee the O2 sensore failing, coming back then erroring again..

I'll get the code the next time it happens..

Cheers

MarkeR · 9 Jun 2016 at 20:52

The code is P0171 if anyone can help.

Thx

Diddums · 9 Jun 2016 at 21:09

I have no idea what's what, but a quick Google found this

http://mbworld.org/forums/c-class-w203/170473-p0171-system-too-lean-obd-code.html

Seems you're on the right track with a sensor, hopefully someone more knowledgeable than me can help out. Good luck

Six6siX · 9 Jun 2016 at 22:40

If you've recently replaced the MAF, check all intake hoses etc are back on properly or that any aren't loose or split - could be an air leak.