W205 NOx Sensors Fail

[Ronmac]

Hi All
I have a 2015 C250 Bluetec Sport
While I was driving last night my engine management light came on. When I got home I checked the error codes they were, P2201 Powertrain NOx sensor circuit range/performance Bank 1 Sensor 1, and P229F Powertrain NOx sensor circuit range/performance Bank 1 Sensor 2. Does this mean both NOx sensors are shot because is it not strange that they would both go at the same time. Is there anything else you can suggest it could be as I am not looking forward to a bill of over £1000 just because the car is six months out of warranty.

 

[clk320x]

They really ****ed these cars with the emissions control bs

 

[BlackC55]

It isnt unheard of for both to go at the same time. the last ones I priced up were £550+ vat each. It was in a car just out of warranty and the customer had no offer of help from MB, its horrendous!
Natacha

 

[ernie]

Hi All
I have a 2015 C250 Bluetec Sport
While I was driving last night my engine management light came on. When I got home I checked the error codes they were, P2201 Powertrain NOx sensor circuit range/performance Bank 1 Sensor 1, and P229F Powertrain NOx sensor circuit range/performance Bank 1 Sensor 2. Does this mean both NOx sensors are shot because is it not strange that they would both go at the same time. Is there anything else you can suggest it could be as I am not looking forward to a bill of over £1000 just because the car is six months out of warranty.

One of mine went at 27k miles 2 weeks out of warranty. As they had been superceded, due to known problems, both had to be replaced as they needed to match. My extended warranty covered the repair, although MB Grangemouth thought that MB might have covered some of the cost under goodwill. MB recognised some of the originals as a problem, so it might be worth trying a different dealership.

Ernie

 

[grober]

NOX sensor SCN coding

 

[Deletedmember130310]

It isnt unheard of for both to go at the same time. the last ones I priced up were £550+ vat each. It was in a car just out of warranty and the customer had no offer of help from MB, its horrendous!
Natacha

Just had mine fail (one on each bank) and been quoted the same..

My dealer proactively asked MB UK for a contribution but this was rejected...

 

[fabes]

Must be something in the water (or air)

Last month I had one go
Nigh on £400 for the bleepin part

 

[clk320x]

Must be something in the water (or air)

Last month I had one go
Nigh on £400 for the bleepin part

Damn!

 

[grober]

Must be something in the water (or air)

Last month I had one go
Nigh on £400 for the bleepin part

Interesting discussion here about the catastrophic effect of water vapour in the exhaust gas damaging NOx sensors.
http://prounit.info/wp-content/uplo...or-and-monitor-CM2150-2220English-version.pdf
And we have had a recent spell of extremely hot/humid weather and hotter air carries more water vapour?? Not suggesting this was the sole cause of the recent spate of failures but might hvae been enough to push a few dodgy ones over the edge ?

 

[grober]

Excerpt from above article

NOx sensor functionality.
At key-on the NOx sensor heats up to 100C.
It then waits for a “Dew Point” signal from the engine ECM.ƒ
“Dew Point” is the point after which there is no moisture or
condensation in the exhaust that would cause the NOX sensor to
fail. The dew point is currently set to 120C. This measurement is
taken from the outlet EGP temperature sensor.
When the dew point signal is received from the Engine ECM the
sensor then heats up to 800C. Note: Water contact at this point will
damage the sensor.
from the above it would seem that the dew point setting and the proper functioning of
one or more associated exhaust temperature sensors situated before the NOx sensor are important to its long term survival?

 

[sturgeon]

Too fragile for real world use?

 

[grober]

This is a good introduction to the complexity of these systems as seen by MB computer. Its for a
Diesel Sprinter 642 CDI, and things will have undoubtedly changed since then, but you will get the idea!

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[sturgeon]

I wonder what the cost of monitoring over 700 miles is? Let alone the rest of it!!!

 

[Ronmac]

Update on my NOx sensor problem I took the car to Mercedes BMW Audi Independent Specialists in Glasgow they put it on their Star Diagnostics and told me that both NOx sensors were faulty and would have to be replaced. They said that this is the 3rd C Class with this problem in a month and that the other 2 were replaced by Mercedes dealerships at no cost as early versions of the sensors were of questionable quality and there was also a software update needed to run the new sensors. Apparently there was a service note about this issued to dealerships does anyone know anything about this ? At the moment I am waiting for a response from MB cars UK to my request for this to be done free of charge.

 

[Andyfkettle]

Had them done on my s205.
Drove back from Benz on the green back to the midlands no problems.
Next day engine light on. Took to merc for diagnostic.
Week later goes in when parts in stock, went later to collect the car and apparently they received the wrong part so had to re-order.
I’m guessing it needed second sensor aswell.
Two weeks later all sorted.
On a German forum I’m on everyone’s had exactly the same and there’s a lot of them.

 

[ktos92]

I have hear that all the early models of W205 had a NOX sensors replaced on the warranty. It seems it is similar problem as with BMW :-D

 

[Ronmac]

On going, car recovered by MB to MB Glasgow in Milton Street yesterday phoned 5 times today got no response from breakdown department took 3 calls before they acknowledge my car was actually there. ... WATCH THIS SPACE

 

[JimCl]

Update on my NOx sensor problem I took the car to Mercedes BMW Audi Independent Specialists in Glasgow they put it on their Star Diagnostics and told me that both NOx sensors were faulty and would have to be replaced. They said that this is the 3rd C Class with this problem in a month and that the other 2 were replaced by Mercedes dealerships at no cost as early versions of the sensors were of questionable quality and there was also a software update needed to run the new sensors. Apparently there was a service note about this issued to dealerships does anyone know anything about this ? At the moment I am waiting for a response from MB cars UK to my request for this to be done free of charge.

HI I have just had the same problem with my Mercedes 220C Class Bluetec Auto Jan 2015 W205 model. I took it to Mercedes Sunderland today 10th Sept 2018 and had a Diagnostic check done (£95).
They confirmed my suspicions that both the Upstream and Downstream NOx sensors were faulty.I expected to be told it would cost £1200+ as I had priced them earlier.
However to my surprise I was told that Mercedes would bear the total cost and I would not have to pay a single penny and they had replaced them both. Needless to say I was doing CARTWHEELS I was very pleased!!!. I was only there 2hrs. Fantastic!.
In conclusion I would say that Mercedes have realized this is a problem as my car is over 8 months out of its waranty.
I would take your car to a Mercedes dealer and ask if they would do yours for free as a Goodwill gesture.Good luck!.

 

[steve333]

HI I have just had the same problem with my Mercedes 220C Class Bluetec Auto Jan 2015 W205 model. I took it to Mercedes Sunderland today 10th Sept 2018 and had a Diagnostic check done (£95).
They confirmed my suspicions that both the Upstream and Downstream NOx sensors were faulty.I expected to be told it would cost £1200+ as I had priced them earlier.
However to my surprise I was told that Mercedes would bear the total cost and I would not have to pay a single penny and they had replaced them both. Needless to say I was doing CARTWHEELS I was very pleased!!!. I was only there 2hrs. Fantastic!.
In conclusion I would say that Mercedes have realized this is a problem as my car is over 8 months out of its waranty.
I would take your car to a Mercedes dealer and ask if they would do yours for free as a Goodwill gesture.Good luck!.

Does anyone know if the replacement nox sensors are superior to the originals as both mine and my wife's E220 bluetec(both 65 plates) have had box sensors go thankfully under warranty.

 

[grober]

Another treatise on NOx sensors here.
NOx Sensors

As said before these are essentially two lambda sensors one after the other. You will see from the diagram that the first cell's function is to remove all oxygenated species from entering the second part of the unit other than NOx so it can be accurately measured
Now previously I had said these can be badly affected by excess water in the exhaust so the exhaust stream had to be up to temperature before they were switched on but perhaps that was innaccurate maybe instead of water I should have said " oxygenated species" which would have included ethanol! Ethanol in petrol at 5% levels is pretty much a given in 95 octane in most petrol blends now. [so called E5 fuel possibly to be E10 =10% ethanol shortly!] One of its less desirable properties is its deliquescent -it absorbs water when exposed to air--- [ this is already knocking out scores of carburettors in small petrol driven appliances since its introduction!] so there is scope perhaps to include ethanol containing fuel as a possible culprit for early NOx sensor demise? What about diesel you ask it doesn't contain ethanol??? True --- all I can suggest there is the prolonged engine and exhaust warmup time of diesel exhausts compared to petrol may be a factor in those compression ignition engines.