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Two days ago my CEL came on and I have code P229F. It's a 2015 GLK 250. From searching it seems that it is referring to NOX sensor bank 2. My google fu is failing me, because I can't find anything saying where this is. As far as I can tell, there are two sensors going into the muffler, in a location about the middle of the rear doors - one on the driver side, one on the passenger side. I'd like to try to take it out and clean it, but I don't know which one it is. Or is it somewhere else? Any help would be very much appreciated!
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Hmmm. Strange. the little bit of searching I did shows conflicting info of whether it's on Bank 1 or Bank 2. For example here's one that breaks down character, than summarizes :
"OBD2 Diagnostic Trouble Code P229F means that NOx Sensor Circuit Range/Performance (Bank 1 Sensor 2) has been detected."
Then another has (for a Sprinter):
"The Mercedes' ECM throws the P229F code when it detects a lower-than-expected voltage signal from the Bank 1 sensor. In general the diesel or AdBlue fluid may be dirty or contaminated, the wrong type or added in incorrect doses."
And another:
"P229F P229F62 P229F63 P229F92 P229FE1 P229E11 and P229e error code stands for NOx sensor circuit range performance issue at bank 2."
But most all agree it's the Downstream sensor because it's the one that'll get the dirtiest.
Maybe clean both Downstream sensors (what I'd do).
I'm not sure what the O2 sensor layout is on the diesel - I'm not even sure there IS a downstream sensor. The NOx sensor is pretty spendy, and (from what I can see) is listed as "upstream" - though again, I'm clueless on the layout on the diesel GLK variant.
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by habbyguy
I'm not sure what the O2 sensor layout is on the diesel - I'm not even sure there IS a downstream sensor.
Okay ... am I completely rwong about my understanding??? I thought diesels were more inclined to have upstream and downstream sensors (?) Guess I should go dig up those links I happened upon prior to my reply ... cause they were oriented to the diesels, like the Sprinter
Nope, looks like you were right (there are apparently downstream sensors on the GLK 250 diesel). I did find this diagram that was very informative (to me, starting at ground zero, anyway)...
If you've had the Emissions Field Measure done this problem should be covered by the associated extended warranty. Here is a PDF of the coverage (this is the Canadian version, the US one is very similar)
I forgot to swing back around to this, but karmikan was correct. I took it to the dealership and it turned out both the nox sensor and the DEF fuel pump needed to be replaced. Both were replaced under the Emissions Field Measure extended warranty and cost me nothing. Whew!
I like reading good news. Here’s one that will throw you for a loop. My 15 250 GLK check engine light was coming on intermittently. I couldn’t figure out the cause with different driving situations. So I go to Auto Zone for a quick diagnostic code reading. Dude said it needed a new oxygen sensor (he didn’t provide a code). I went to the dealer to confirm and came back saying I don’t need a sensor, it needed a new turbo!? 🤔
He said no worries it’s covered with emissions warranty all free + loaner provided. I wonder if I should ask them to replace other stuff.
Wow, that's awesome! And really good to to know that the turbos are also covered under this warranty. Wouldn't that be great if we could go to the dealer and say "Please just replace all the stuff that's going to fail so we can have reliable vehicles again?" lol. Still, I'm happy to hear that. Not as happy as I'm sure you were tho to hear the turbos were covered
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