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Thread: 451 cdi exhaust temperature sensors

  1. #1
    Join Date
    Jun 2011
    Location
    Stafford UK
    Posts
    214

    451 cdi exhaust temperature sensors

    What happened went to work arrived the car went into regen mode so i left it running. When to clock in get my truck keys etc.
    Only away 15 mins noticed the revs had dropped switched it off. Finished work jumped it and started the car engine light stayed on. No drop in power or safe mode. So pluged in a blue tooth OBD and torque pro on me phone. Brings up exhaust sensor 1084 . So i have changed the one on the exhaust for a new one. The new one i checked with a multimeter on ohms it read about 280 . And the old one read nothing . So asume the old one buggered . I soaked the one on the turbo and broke it free ready to change. Can get to that one from underneath. So don't have to take all the panels off. Engine light still on . Will it need to go onto the mercedes Star computor to clear the ECU faults . Going to change the turbo sensor just to be on the safe side. Cheaper me do it than Mercedes. Has any one done these sensors before. Just to say the pressure sensor was done about 8 months ago by mercedes it went into safe mode on that.

  2. #2
    Join Date
    Apr 2009
    Location
    Ecosse
    Posts
    3,571
    On a 450 the EML will extinguish after a few starts once what caused it to illuminate is rectified. But you have a 451...

  3. #3
    Join Date
    Mar 2012
    Location
    Burnley
    Posts
    1,330
    Why do you think that when the engine revs increase from around 800 to around 1100 that it is going into regen?

    From what I have seen it is only keeping the cat at a reasonable temperature. No way will the DPF reach 400 + centigrade at 1100 RPM and that is the minimum it needs.

  4. #4
    Join Date
    Jun 2011
    Location
    Stafford UK
    Posts
    214
    Only going on the info that Mercedes say what happens. I know that it used to get quite hot when it increased the rpm,s Just tryiny to get some information if another owner has changed the sensors and what happened.

  5. #5
    Join Date
    Mar 2012
    Location
    Burnley
    Posts
    1,330
    I am quite sure you do not need to have the faults cleared, the engine lamp will go out after a few starts.

    Do you have a link to where Mercedes say it is doing a regen? I have googled it and asked other people and it only seems to be "what I saw on the Internet" which to me makes it not a fact until there is further evidence.

    My car seems to stay there, at 1100 for ever if I leave it, it will not return to 800 again until I go somewhere and if I stop it when it is at 1100 then it is at 1100 when I start it again.

  6. #6
    Join Date
    Jun 2011
    Location
    Stafford UK
    Posts
    214
    All sorted now replaced the turbo temperature sensor this morning. EML now out running good . Looking at replacing it soon . Doing alot of fishing and its just to small for getting rod bags in. So if anyone interested in a 2010 cdi rally red with 2012 colour coded sills and front spoiler and rear valance. Service history 35000 miles and its Pulse paddle shift and it got the electric power steering. The tridion is wrapped in red carbon fiber. So all red . PM me for price not asking alot.

  7. #7
    Join Date
    Jun 2011
    Location
    Stafford UK
    Posts
    214
    Update on changing the sensors. The car runs hotter now before it was a constant 70 degrees now runs at 80 degrees and seems smoother . Mpg has increased going by the gauge but will do a fill up and check . So i think if you have a problem with the revs going up to 1100rpm often and staying there for lengthy periods . It might be that the sensors are on the way out and giving the wrong info to the computer about the temperatures . This is my take on this. But not found any info or comments by people that have changed the sensors.

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