Presumabily NOX Sensors - ML350 Bluetek 2012 ADBLUE

Discussion in 'Parts, Maintenance & Servicing' started by Lucio, Jan 23, 2020.

  1. Lucio

    Lucio New Member

    Messages:
    6
    Joined:
    Nov 21, 2019
    Location:
    Windsor
    Car:
    ML350 bluetec
    Hi All

    I have been struggling with an issue for the last few week with my wife's ML, as the MIL light switched on and the electronic display is warning that the car won't start in 400 miles!

    I have searched the web but not a lot of specifics on this topic to help and guide me to a solution.

    I have used a MaxiScan MS509 scanner and managed to read two generic codes:
    1. P2BA8
    2. P2BAD
    I have managed to follow some documentation on line and I have identified both sensors, removed and cleaned them, and made sure all electrical connections were intact. I have reset the codes, but no success.

    By the way, the AdBlue tank has been refilled and fuses checked!

    Whilst doing this work, I did a couple of tests by disconnecting each of the sensor's computer from the car, and run the scanner again and read the following codes:
    1. U029E (Sensor furthest from the engine)
    2. U029D (Sensor closest to the engine)
    I also identified the part numbers for the sensors (phots included).
    1. A0009053603 (Sensor furthest from the engine)
    2. A0009053503 (Sensor closest to the engine)
    I have some questions before I bite the bullet and buy the sensors.
    1. Am I right to assume that this is the fault - sensor?
    2. I read that I need to change both sensors - is this correct?
    3. Do I need to re-start/program the new sensors or is this just a straight swap?
    4. Is there a cheap scan that I can use to reprogram the sensors after the swap?
    5. Is it worth buying it second hand or like I said "bite the bullet" and buy 2 new sensors?
    6. Do you have a supplier to recommend that has a less expensive price pls?
    Many Thanks

    Lucio

    UNADJUSTEDNONRAW_thumb_120b.jpg UNADJUSTEDNONRAW_thumb_120c.jpg
     
  2. OP
    OP
    Lucio

    Lucio New Member

    Messages:
    6
    Joined:
    Nov 21, 2019
    Location:
    Windsor
    Car:
    ML350 bluetec
    Hi Guys

    Any here will be appreciated pls.

    Thanks

    Lucio
     
  3. Tramper

    Tramper Hardcore MB Enthusiast

    Messages:
    139
    Joined:
    Feb 2, 2019
    Location:
    Essex
    Car:
    E Class
    Had the same problem with my W212. Both Nox sensors replaced sorted it.
     
  4. tonysurf

    tonysurf Hardcore MB Enthusiast

    Messages:
    112
    Joined:
    May 25, 2009
    Location:
    SE London
    Car:
    E Class Cab
    Does the car have MB service history, my NOX sensors registered the same problem as yours, MB replaced both under goodwill warranty. Saw the invoice price as around £750 lucky escape.
     
  5. OP
    OP
    Lucio

    Lucio New Member

    Messages:
    6
    Joined:
    Nov 21, 2019
    Location:
    Windsor
    Car:
    ML350 bluetec
    Hi all

    thank you, no service history!

    @Tramper did you just swap or did you have to reset it also?

    Thanks

    Lucio
     
  6. OP
    OP
    Lucio

    Lucio New Member

    Messages:
    6
    Joined:
    Nov 21, 2019
    Location:
    Windsor
    Car:
    ML350 bluetec
    MrGreedy, Peter103 and Abb like this.
  7. Abb

    Abb Hardcore MB Enthusiast

    Messages:
    3,017
    Joined:
    Aug 28, 2013
    Location:
    UK
    Car:
    Mercedes
    Was it a straight forward job to replace them? If so, seems like a bargain you have got yourself there. There are several posts on here where MB have charged/quoted anywhere between £1K-£2K to have both Nox sensors replaced!
     

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