NOx sensor & oil leak E250 2014 (77K MI)
Thread Starter
Junior Member
Joined: Jan 2019
Posts: 20
Likes: 6
2014 E250
NOx sensor & oil leak E250 2014 (77K MI)
Just got a code P2201 (using my icarsoft ) on my 2014 E250. Took the car to MB dealer. Dealer confirmed code P2201E1, dealer replaced up and down stream NOx sensor with updated version according to invoice. Also “performed CDI software update with updated SCN coding to Add 30o?” Not sure what this means. They: “road tested the car and found a 4:1 reduction through the SCR system. Car operating normally”. Part # 905-34-03 and “ 905-35-03.
Also, the last time I had the belly pans off the car I noticed oil seeping at drivers side of car, just a drop or so. I mentioned this to the dealer and dealer replaced two seal rings and two gaskets plus one metal seal. The description calls the parts upper and lower O-rings between mixing chamber and throttle valve. Part (# 651-091-04-60) (651 091-02-60) (651-142-04-80)
( 651-142-24-80).
All of the above work was no cost to me, my extended warranty covered the repairs. Possibly emissions warranty covered NOx sensors but invoice does not say.
Hope this helps someone in the future.
Also, the last time I had the belly pans off the car I noticed oil seeping at drivers side of car, just a drop or so. I mentioned this to the dealer and dealer replaced two seal rings and two gaskets plus one metal seal. The description calls the parts upper and lower O-rings between mixing chamber and throttle valve. Part (# 651-091-04-60) (651 091-02-60) (651-142-04-80)
( 651-142-24-80).
All of the above work was no cost to me, my extended warranty covered the repairs. Possibly emissions warranty covered NOx sensors but invoice does not say.
Hope this helps someone in the future.
Senior Member
Joined: Jul 2017
Posts: 487
Likes: 114
From: DFW, TX
Ml350 bluetec
MB has been sketchy with warranty work on their NOX sensors. It depends on which year the vehicle was made. You need to look at the owners/warranty manual to see what is covered or not covered. In the case of my 2014, they DO NOT cover the NOX sensors, explicitly stated. So at this point I just drive around with the CEL online. The o-rings in question for the oil leak is typical "maintenance" items. You got lucky that they covered those under extended warranty. Again depending on the extended warranty, these are not always covered.
Thread Starter
Junior Member
Joined: Jan 2019
Posts: 20
Likes: 6
2014 E250
I guess I got lucky. Not sure what the repairs would have cost if paying out of pocket, glad the MB warranty covered the repairs. I hope the new NOx sensors last for years, I hope to keep this car for years. The oil is changed every 5K, and I monitor the DPF with a Scan Gauge. The DEF tank heater was also replaced under warranty just a few month ago.
Senior Member
Joined: Jul 2017
Posts: 487
Likes: 114
From: DFW, TX
Ml350 bluetec
NOX sensors the last time I looked for both front and back was around $1200ish parts and labour. The only way I know of to keep the NOX sensors clean is to drive it like you stole it. I previously drove a 2013 VW Touareg TDI. It too developed CEL for the NOX sensors, and I found if I floored it around a lot, the CEL would disappear. However it would come back if I drove it in a sedate manner. This same also applies to keeping soot levels down with the DPF. Drive it a lot and as long as possible, keep the short city trips to a minimum will give the DPF system a chance to heat up and burn off the soot.
But otherwise good luck with your vehicle.
But otherwise good luck with your vehicle.
