P0087
Thread Starter
Newbie
Joined: Mar 2025
Posts: 3
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E350 W212
P0087
Hi guys/girls,
I'm hoping you can help, I'm at my wits end with this car!
E350 W212 Blue Efficency
Issues started when we bought the car, P0087 fault code, lots of power but would randomly cut out, would start immediately again and we could keep driving. Took it into a garage, they diagnosed a faulty fuel rail to be the issue, replace that and it'll fix all our problems. We replaced both fuel rails and it cuts out less now, but it's in limp mode and sometimes still cuts out under hard acceleration. Another visit to a second garage, they ran a xentry report saying the issue was due to us not performing a necessary adaption to a fuel rail sensor when the rail was changed, whatever that means?! The garage was unable/unwilling to help beyond a xentry print out. Cue a trip to a 3rd garage, who said it was definitely the diverter valve on the high pressure pump causing the problem, so we replaced the diverter valve which made no difference. Lots of googling between garage visits has seen us replacing most of the fuel system and testing the rest. 2x fuel rails with all hard lines, 1x high pressure pump, 1x saddle pump in the tank, 1x diverter valve, 1x fuel pressure sensor, 1x fuel pressure regulator, 1x fuel filter, and testing high pressure fuel pump, all injectors with leakback test and high pressure tests. I have new printouts from xentry but they don't mean a whole lot to anybody and we've ran out of local Mercedes experts to ask for help. All the garages we've been to so far "specialise" in Mercedes, but none have any idea.
Has anybody got any idea what's causing the issues here? Has anybody got any idea of what direction to now look in?
Thanks
I'm hoping you can help, I'm at my wits end with this car!
E350 W212 Blue Efficency
Issues started when we bought the car, P0087 fault code, lots of power but would randomly cut out, would start immediately again and we could keep driving. Took it into a garage, they diagnosed a faulty fuel rail to be the issue, replace that and it'll fix all our problems. We replaced both fuel rails and it cuts out less now, but it's in limp mode and sometimes still cuts out under hard acceleration. Another visit to a second garage, they ran a xentry report saying the issue was due to us not performing a necessary adaption to a fuel rail sensor when the rail was changed, whatever that means?! The garage was unable/unwilling to help beyond a xentry print out. Cue a trip to a 3rd garage, who said it was definitely the diverter valve on the high pressure pump causing the problem, so we replaced the diverter valve which made no difference. Lots of googling between garage visits has seen us replacing most of the fuel system and testing the rest. 2x fuel rails with all hard lines, 1x high pressure pump, 1x saddle pump in the tank, 1x diverter valve, 1x fuel pressure sensor, 1x fuel pressure regulator, 1x fuel filter, and testing high pressure fuel pump, all injectors with leakback test and high pressure tests. I have new printouts from xentry but they don't mean a whole lot to anybody and we've ran out of local Mercedes experts to ask for help. All the garages we've been to so far "specialise" in Mercedes, but none have any idea.
Has anybody got any idea what's causing the issues here? Has anybody got any idea of what direction to now look in?
Thanks
Last edited by jageshemash; Mar 26, 2025 at 02:47 PM.
Senior Member
Joined: Apr 2016
Posts: 457
Likes: 151
From: Phoenix, AZ
2016 E350 Sport 2WD
You posted Lots of good information.
Maybe something here will help"
https://www.benzworld.org/threads/p0...o-low.2446665/
Maybe something here will help"
https://www.benzworld.org/threads/p0...o-low.2446665/
Senior Member
Joined: Apr 2016
Posts: 457
Likes: 151
From: Phoenix, AZ
2016 E350 Sport 2WD
I don't know as much about Mercedes engines as I do about Chevy Duramax engines, but many people with Duramax engines have a similar problem and replace a lot of parts, just like you did. In a Duramax engine, the fuel pump itself could be 'good, ' but if the injectors bypass too much fuel back to the fuel tank (usually under high load conditions), the pump just won't keep up with the demand. So, in that case, the 'fix' is to replace the fuel injectors. Another thing that is sometimes missed but not very common is that the electrical supply to the fuel pressure regulator drops lower or out, and the regulator doesn't do the expected job. Not many people think to check the computer's power feed to the regulator. And another problem is Duramax engines operate by sucking fuel from the tank to the engine and the rubber fuel lines can be sucked shut in high temps when they age. Said another way, there is a fuel restiction.
This may not help much, but perhaps it's something to think about
This may not help much, but perhaps it's something to think about
Junior Member
Joined: Mar 2025
Posts: 16
Likes: 8
OM642 is in fact diesel, yes. Fun motors.
Anyways, the intermittency of the issue leads me to believe it to be electrical - primarily fuel pressure sensor or PCM related (as the end symptoms). Let me divulge.
If it's an immediate cut out, you're very likely looking at electrical; if there's some tenuation before cutting out, only then would I consider a hydro-mechanical problem (fuel delivery).
That being said I'd look for voltage spikes or cut outs during load/failure. It wasn't listed on the freeze frame data, and that's not what we're looking for Mercedes... It is possible the alternator or readings at FPS would be out of normal range - I've seen it happen before, I would start there.
Pending voltage is normal during the failures, then consider harness issues, do a dynamic position harness continuity test and following that consider the PCM.
I'm very heavily leaning towards a power supply issue considering it sounds like an immediate failure, maybe the VR is going out just enough to cause spike and cause a shut off - I have seen it before and have seen bad EPS unit cause a shut off on a Mazda, BMW VANOS codes then limp mode, heavy load/throttle/engine cutoff on a Honda, the list goes on..
The PCMs on these don't have a high failure rate, but I have heard of rodent issues with these as well - something to consider. Good luck and keep us updated
Anyways, the intermittency of the issue leads me to believe it to be electrical - primarily fuel pressure sensor or PCM related (as the end symptoms). Let me divulge.
If it's an immediate cut out, you're very likely looking at electrical; if there's some tenuation before cutting out, only then would I consider a hydro-mechanical problem (fuel delivery).
That being said I'd look for voltage spikes or cut outs during load/failure. It wasn't listed on the freeze frame data, and that's not what we're looking for Mercedes... It is possible the alternator or readings at FPS would be out of normal range - I've seen it happen before, I would start there.
Pending voltage is normal during the failures, then consider harness issues, do a dynamic position harness continuity test and following that consider the PCM.
I'm very heavily leaning towards a power supply issue considering it sounds like an immediate failure, maybe the VR is going out just enough to cause spike and cause a shut off - I have seen it before and have seen bad EPS unit cause a shut off on a Mazda, BMW VANOS codes then limp mode, heavy load/throttle/engine cutoff on a Honda, the list goes on..
The PCMs on these don't have a high failure rate, but I have heard of rodent issues with these as well - something to consider. Good luck and keep us updated
Last edited by BBBAAUTO; Mar 27, 2025 at 06:50 AM.
Joined: Nov 2016
Posts: 7,847
Likes: 3,496
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
There are no DTCs for the fuel pump (N118 - Control unit 'Fuel pump' (FSCU05)). So, the problem is more likely on the fuel rail/fuel injector end. There was no mention of replacing the injectors. Of course, enough parts have been throwned at this problem already. However, injectors are still a rock unturned.
Thread Starter
Newbie
Joined: Mar 2025
Posts: 3
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E350 W212
There are no DTCs for the fuel pump (N118 - Control unit 'Fuel pump' (FSCU05)). So, the problem is more likely on the fuel rail/fuel injector end. There was no mention of replacing the injectors. Of course, enough parts have been throwned at this problem already. However, injectors are still a rock unturned.
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Thread Starter
Newbie
Joined: Mar 2025
Posts: 3
Likes: 0
E350 W212
OM642 is in fact diesel, yes. Fun motors.
Anyways, the intermittency of the issue leads me to believe it to be electrical - primarily fuel pressure sensor or PCM related (as the end symptoms). Let me divulge.
If it's an immediate cut out, you're very likely looking at electrical; if there's some tenuation before cutting out, only then would I consider a hydro-mechanical problem (fuel delivery).
That being said I'd look for voltage spikes or cut outs during load/failure. It wasn't listed on the freeze frame data, and that's not what we're looking for Mercedes... It is possible the alternator or readings at FPS would be out of normal range - I've seen it happen before, I would start there.
Pending voltage is normal during the failures, then consider harness issues, do a dynamic position harness continuity test and following that consider the PCM.
I'm very heavily leaning towards a power supply issue considering it sounds like an immediate failure, maybe the VR is going out just enough to cause spike and cause a shut off - I have seen it before and have seen bad EPS unit cause a shut off on a Mazda, BMW VANOS codes then limp mode, heavy load/throttle/engine cutoff on a Honda, the list goes on..
The PCMs on these don't have a high failure rate, but I have heard of rodent issues with these as well - something to consider. Good luck and keep us updated
Anyways, the intermittency of the issue leads me to believe it to be electrical - primarily fuel pressure sensor or PCM related (as the end symptoms). Let me divulge.
If it's an immediate cut out, you're very likely looking at electrical; if there's some tenuation before cutting out, only then would I consider a hydro-mechanical problem (fuel delivery).
That being said I'd look for voltage spikes or cut outs during load/failure. It wasn't listed on the freeze frame data, and that's not what we're looking for Mercedes... It is possible the alternator or readings at FPS would be out of normal range - I've seen it happen before, I would start there.
Pending voltage is normal during the failures, then consider harness issues, do a dynamic position harness continuity test and following that consider the PCM.
I'm very heavily leaning towards a power supply issue considering it sounds like an immediate failure, maybe the VR is going out just enough to cause spike and cause a shut off - I have seen it before and have seen bad EPS unit cause a shut off on a Mazda, BMW VANOS codes then limp mode, heavy load/throttle/engine cutoff on a Honda, the list goes on..
The PCMs on these don't have a high failure rate, but I have heard of rodent issues with these as well - something to consider. Good luck and keep us updated
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Joined: Nov 2016
Posts: 7,847
Likes: 3,496
From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
