Potrice

Hey everyone...

My BIL is still having CEL issues. P2201 code CEL pops up even after having 2 new NOx sensors installed (by myself and got them off amazon). At first I thought it was because it needed online coding/readaptation from the MB dealership. Well after his appointment, the dreaded CEL came back with the same code! What the heck? I guess it would either be a wiring issue or a faulty brand new sensor?

Has anyone experienced this before? 2013 ML350 BT. Around 135 000 km...

My first step will be contacting the company (GERMBAN) for a warranty claim on both sensors (they come with 2 years warranty). While the new sensors are on their way, I'll check the wiring from the sensor module all the way to the back/front of the car. Is it possible all of this is caused by a wiring issue (in the trunk near the spare tire where the control unit is)? Maybe a fuse?

Diabolis

If they are not OEM sensors, all bets are off. When it comes to electrical bits, I wouldn't touch anything except OEM... seen way too many that don't work.

Is P2201 the only code? Where does he fill up -- what brand diesel fuel is in the car? I know of several instances of that code coming up as a result of the fuel having more than 5% biodiesel content and then disappearing after good fuel is put back in (IIRC it takes a full tank and six starts for the condition to clear itself). Unfortunately with the cheap NOX sensors you can't eliminate then as being the cause.

Potrice

Hey Diabolis,

Thanks for the informative response. P2201 is the only code popping up. Regarding the diesel well, he fills up at Ultramard (-2c on Tuesdays). As far as I know, they don’t use biodiesel...

I’ll initiate a warranty claim/return on the sensors and try my luck with another batch...worst case scenario I’ll order OEM sensors. I’ll also check for wiring issues just to rule that out...

Diabolis

All suppliers in Canada use some amount of biodiesel (the usual is around 5% or B5; Ontario mandates a minimum of 4% biodiesel content). Biodiesel combustion produces higher NOx emissions than traditional diesel, hence you may get said code on fuel with higher biodiesel content which is becoming more and more common in the US where corn production is heavily subsidized. Ultramar is Parkland-owned, which sources its fuel from multiple suppliers so the fuel quality is not as consistent as the big names in the industry, but it is still normal B5 diesel... we're not talking fine red wine here. You can ask him to fill up at a different station next time to see if it makes a difference, but I highly doubt it.

If there are no other codes I'd still be barking at the NOx sensors. DAS Xentry would show you what the readings are (plus you need it to do the adaptation anyway), but I gather you don't have it. The OEM sensors are unfortunately not cheap (about $2K CAD for both), but that's the price of owning a Mercedes.

zemun1234

As for buying NoX sensor, the price in Canada is 836 CND + 13 % tax and I purchased both sensors in USA (300 USD back + 400 $ front - speaking from memory). If you are going buy sensors, you can try that. I got problem with one sensor but I have changed both once I get reasonable price (I didn't want pay 2x adaption and other 'best or nothing' BS). The next time when I get similar problem, I am going invest in DPF/EGR delete

I agree with Diabolis about quality of diesel. I stick with one brand (Petro Canada) and usually, I try to fill on same gas station (if possible).

charles.soori

its common for aftermarket nox to throw error, sometimes bad cat can cause nox error as well. i'm even surprised dealer did scn coding for you on a aftermarket nox. another option is to delete adblue off complete.

Potrice

Well I contacted the Amazon seller and he apologized and is sending me a brand new front NOx sensor at no cost. It should arrive today. Fingers crossed it will fix the CEL issue...I'll keep this thread updated...

rafid

HI

I also need to replace the nox sensors and I was considering to buy the same one you bought from amazon.
did you solve the problem?
the sensor they sent you was defective?

Potrice

Still hasn’t worked. He’s throwing in the white towel and going the delete route.