Mercedes - P0193 error - Anyone Know Where to Get Generic /OEM Mercedes Parts - Pressure Switch and Eye Watering $3000!

tunzafun001 on 28/10/2022 - 16:11

Hi all,

My old man (70) has always wanted a Merc. Not even close to being able to afford a new one, but recently bought a used 2012 Merc 350 GL - Diesel.

What a piece of rubbish…just fixed and oil cooler leak…American made engine is a disgrace to to work on! Local mechanics weren't interested in doing the job (don't blaim them as lots of bleeding was involved just to get the turbo out). This engine doesn't match the car (no room to undo the rear bolts). Rubbish design in every way.

Anyway, putting everything back together, the car runs, but is limited to 3000 rpm and returning an error code of P0193 - High fuel pressure rail.

I reset it, but it comes straight back.

Just got a price from Mercedes for the basic switch $2000 …for a switch!…and $900 for the other (sensor), as it could be either of them causing the problem.

Just ridiculous for a switch! Hopefully someone knows some generic alternatives.

I actually don't even think thats the problem, unless some rubbish/ air got in there when we disconnected the fuel rail. Don't know.

But $3000 for a couple of switches is a very expensive maybe fix. He has made a huge mistake.

Cheers

Automotive Automotive Parts Mercedes-Benz

Comments

  • brendanm on 28/10/2022 - 16:13
    +4

    So it was working fine before you repaired the oil cooler leak? Sure you have the right plug on the right sensor?

    • tunzafun001 on 29/10/2022 - 00:11

      Yeah, plug only goes one way. Possibly some crud entered the diesel rail and lodged in the sensor. Might be able to clean it up and put back in..

      • popcornready on 29/10/2022 - 08:47

        So the car is crap but the issue wasn’t there till you “self repaired”?

      • brendanm on 29/10/2022 - 09:56

        I'm aware the plug only goes on one way, has the plug been swapped with one for a different sensor? "Crud" in the fuel rail doesn't cause a high rail pressure code.

        • tunzafun001 on 29/10/2022 - 11:19

          I had a look at the sensors online. You are right, nothing to clog there it would seem.

          These Mercs (Aussie version) have 2 sensors/ senders at different ends of the fuel rails. So two possible points of failure….at least.

          Weird anomaly is my old man has a scan tool that shows the fuel pressure (ranging from 5000 - 7000 psi) even when both are disconnected??

          Maybe there is another sensor on the pump itself, but this seems to be in range and all good.

          BUT..when I used my tablet and the Torque app. I get a constant fuel pressure of 31000 psi..sensors plugged in or not. Probably a bug in the app. Backing the scan tool for accuracy.

          However, both scan methods produce the same P0193 fault code, and also the same code (can't remember what it is) when the sender is disconnected. So the sender isn't dead.

          As for the other sensor. It doesn't produce any extra faults if connected or not. Merc mechanic thinks this is because the car is already in limp mode, and doesn't monitor the other sensor in this mode.

          I'm now looking for how to diagnose the sender/ sensors with a multimeter. Unfortunately the second sensor doesn't exist in the Merc workshop manuals (an add on for the Aussie models only apparently). Euro mechanics say they have never seen the sensors fail ever before, but said the codes suggest to replace one/ both.

          Lastly, I'm still leaning towards a bad contact somehow/ somewhere.

          • brendanm on 29/10/2022 - 11:51

            @tunzafun001: Three wire sensor. 5v reference voltage from ecu, ground reference, and a signal return, which will be in the 1.4-4.5v range normally, dependant on fuel pressure obviously.

            On the pump you will have a fuel metering valve. On the rail you will have a pressure sender, and an electronic pressure regulator (this is probably what you are assuming is another sender). What scan tool are you using? A generic is not the best option.

            • tunzafun001 on 30/10/2022 - 15:59

              @brendanm: Thanks for this, and bang on mate. Signal peaks around 4.8v. Think I have found the issue.

              Had a close look and the plastic outer cover has a crack. Looking inside, there are connector pins inside the cover (not just the actual plug pins themself). The ground and power pins make contact, but the signal pin isnt (fatigued a bit, and the crack allows it to move away).
              Ironically, with multimeter leads in the back of the plug, it makes contact, and all looks ok.
              Once removed the contact has a 1mm gap.

              So will order a new sensor. Thanks to the links here, only around $70.

              Mercedes would charge $2k for this..so bad!

              Thanks again mate for your help.

              • brendanm on 30/10/2022 - 19:02

                @tunzafun001: Sensor might have copped a bit of a tweak will doing other work, it happens. Hopefully that sorts it out for you 👍

                • tunzafun001 on 31/10/2022 - 00:16

                  @brendanm: Yeah, definitely my fault. You need to lay across the engine to reach down the back to get to the exhaust / turbo bolts.

                  Just looking at the rail pressure sensor, it looks like almost every manufacturer uses the same sensor? but with a different number, or are they all the same physical size/ shape/ connector (M18x1.5), but monitor a different range?

                  Ie. This on sparesbox. https://www.sparesbox.com.au/part/goss-fuel-rail-pressure-se…

                  vs any generic on ebay.. on ebay https://www.ebay.com.au/itm/195346925698? (Aussie stock)

                  They all look pretty similar. This (china stock only) is the actual part number https://www.ebay.com.au/itm/385180151428? So hoping I can just get the Aussie available version if it's the same?

                  • brendanm on 31/10/2022 - 07:43

                    @tunzafun001: Lots are probably the same, but I'm sure there will be variances in connector type, and there are definitely differences across the working pressure range. Likely also differences in how they seal to the rail.

  • bobbified on 28/10/2022 - 16:22
    +1

    If you can't fix it yourself, might be worth getting it checked out by a euro specialist who might be more familiar with these engines (as opposed Mercedes themselves or a general mechanic).

    • tunzafun001 on 29/10/2022 - 00:13

      Yeah, got a couple of mechanics giving their input (none of them will touch these V6 diesel Merc's…and I don't blame them…shocking design). They only know of the genuine Merc switch.

  • aoeueoa on 28/10/2022 - 16:23

    Sunk cost fallacy…..
    Sure you want to proceed?

  • boomramada on 28/10/2022 - 16:37

    I actually don't even think that's the problem

    Better check with different euro specialist as suggested above, look like issue can be anything according to this
    https://www.carparts.com/blog/p0193-code-fuel-rail-pressure-…

  • Brian McGee on 28/10/2022 - 16:40

    Maybe give premier auto trade a call, they can advise if it's a part they supply, and where you'll be able to order it.

  • Ocker on 28/10/2022 - 16:43

    What are the part numbers?

  • spackbace on 28/10/2022 - 17:01
    +2

    He has made a huge mistake.

    There's the TL;DR

  • Muzeeb on 28/10/2022 - 17:16
    +1

    limited to 3000 rpm

    That's not bad for a diesel.

    Just put up with it until the engine dies completely.

    • tunzafun001 on 29/10/2022 - 00:15

      haha..it's drivable, but the Merc has plenty more revs. Also a bit dangerous.

  • 2jzzzz on 28/10/2022 - 17:24
    +2

    Got mine from the states. Quick delivery very good price, always bought more filters as they were so cheap.

    Site is https://www.fcpeuro.com/

  • pegaxs on 28/10/2022 - 17:26
    +3

    Lol… I love euro cars…

    Not even close to being able to afford a new one

    What’s the saying again kids? If you can’t afford a new euro trashwagen, you definitely can’t afford a used one.

    Buy parts for your shitbox out of Europe or UK. Much much cheaper and it’s where I source a lot of parts for customers cars. Can take some time to get here, but if you’re saving big $$’s

    But you are gonna spew when you find it’s not the sensors and it’s the high pressure fuel pump…

    • tunzafun001 on 29/10/2022 - 00:19

      I've ruled out the fuel pump itself, as I can see the actual fuel pressure sits in a good range on the scan tool.

      I truly hate this thing! I have a Mitsi PHEV. 150k km, done nothing but basic service and drove it. Electric motors just keep on spinning.

      • popcornready on 29/10/2022 - 08:49

        Yeh that’s fine re the mitsi, but quick questions: how many kms did the Merc have when your dad bought it? And what price did he pay?

        • tunzafun001 on 30/10/2022 - 22:52

          Around 80k Kms… and too much!

          The leaking oil cooler (and being a pig of a job to fix) is well known.

  • sween64 on 28/10/2022 - 18:13
    +2

    If you head down to Melbourne OzWreck, 50 Bennet Road Dandenong is a cheap auto wrecker. I was hunting for Ford parts though.

    Or Jolly’s has a great website, maybe they deliver..

    • tunzafun001 on 29/10/2022 - 00:20

      Good one mate. Thanks.

  • AB100 on 28/10/2022 - 18:29
    +1

    Have you made sure that the sensor plugs are fully seated, and locked down, not loosely connected. Make sure that the plug connectors and the sensor connectors are clean, also make sure one of the connector(s) hasn't pushed back inside the plug, when you connected it.

    • tunzafun001 on 29/10/2022 - 00:27

      Good idea re push back. Old man chased connections through to ECU with multimeter. Plus, when you actually unplug it, it throws up another code. So appears to be making a connection. Just suss that it was never a thing until now.

      That being said, Mercedes…Ummericuh (America) have the wires bending back 90 degrees and then compressed with a zip tie before entering the plug.
      My mind was blown with how bad the workmanship is in a Merc. This is how it is meant to be (in workshop manual). But we have wiggled while checking continuity.

      But I'm confident it is going to be something like this (as I had to lie across the plug to undo 9 bolts… which you can't see…down a 50mm gap to the firewall..tight as hell), or something entered the fuel rail (as we had to remove the inlet manifold to get to the oil cooler)

  • Drakesy on 28/10/2022 - 18:35

    Take it to an independent euro mechanic, they'd know their way around it without taking you to the cleaners (hopefully).

    I've been burnt hard by an Audi in the past, ever since i wouldn't touch one with a 10 foot pole.
    Although i did find a really competitive independent audi mechanic who i'd go back to if i felt like a masochist. Pretty sure i put his kid through college.

    • tunzafun001 on 29/10/2022 - 00:28

      Got a few around, but they wont touch it. Good call by them. It's a terrible design.

  • Bid Sniper on 28/10/2022 - 18:36

    Imagine being 70, you wanted a Benz all his life

    Then he finally got one

    What a sad story

    PS Cross reference part numbers on Ebay, probably something that's a cheap Chrysler part, I'm serious.

    • knasty on 28/10/2022 - 21:44
      +1

      If that doesn't work you can check fcpeuro.com, pelicanparts.com or spareto.com. I've had good experience with Merc parts from all 3 of them; even with shipping from the US/EU it still works out way cheaper than buying specialty parts locally (if you can even find them).

      • tunzafun001 on 29/10/2022 - 00:29

        Good one, thanks mate. Great leads now. Cheers

      • mini2 on 29/10/2022 - 16:22
        +1

        Pelican's usually cheaper than ECS. Plus if you sign up to their newsletter, you get a 10% off code for your first order.

    • tunzafun001 on 29/10/2022 - 00:34
      +1

      The extra kicker is he is still going through cancer treatment, but hey, plenty of people far worse off at the moment. At least we have the ability to fix it (hopefully)… We'll get it sorted.

  • Euphemistic on 28/10/2022 - 19:48

    Buy another one for parts?

  • skillet on 29/10/2022 - 08:15

    I work on my Audi in most cases where anything involves the side of the engine, the whole powerplant has to come off. They made everything fit just right and no space even for my thin hands. But then again this is a car with higher engine spec and extra cyclinders. Maybe there will be more space if it had the base model engine.

    • Muzeeb on 29/10/2022 - 08:50

      Bi turbo V6?

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