P0191 Fuel Pressure Control Upper Limit - New Pump Fixed It… But Now It’s Back!

Jan 5, 2026 | 05:06 PM

Samuelseggss

Thread Starter

Newbie

Joined: Jan 2026

Posts: 6

Likes: 1

2009 ML63

P0191 Fuel Pressure Control Upper Limit - New Pump Fixed It… But Now It’s Back!

Hey everyone, I’m running into a recurring issue with my 2009 Mercedes ML63 AMG and could use some help.

Symptoms / What Happened:

I was getting P0191 Fuel Pressure Control: The Upper Limit Value is Reached.
After replacing the fuel pump, the error went away for about 2 days.
Now the code came back again.

It’s really frustrating because I had hoped the pump swap would fix it permanently

I’ve seen on other threads that many people recommend replacing the fuel pressure sensor. However, I’m confused about which one I actually need.

Here are the parts I found online but I’m not sure which is correct for my ML63:

OEM / MB Parts:
• https://mbparts.mbusa.com/oem-parts/...sor-1635422818
• https://mbparts.mbusa.com/oem-parts/...ensor-45421618

eBay Options (possible sensors):
• https://www.ebay.com/itm/405395127371
• https://www.ebay.com/itm/40546887234...sor+ML+63+2009
• https://www.ebay.com/itm/40554447186...sor+ML+63+2009
My Questions
1. Which fuel pressure sensor part is the correct one for this P0191 issue on a 2009 ML63?
2. Is there more than one sensor involved (high-pressure rail vs low-pressure/return)?
3. Is it possible that the new pump caused the code to clear temporarily, but the underlying sensor or wiring issue remains?
4. Any known issues with the ML63 fuel pressure sensor harness, connectors, or PCM triggers?

Here is my VIN 4JGBB77E99A455736

Thank you

Last edited by Samuelseggss; Jan 5, 2026 at 06:03 PM.

Jan 5, 2026 | 06:03 PM

Samuelseggss

Thread Starter

Newbie

Joined: Jan 2026

Posts: 6

Likes: 1

2009 ML63

Vin is also included

Jan 5, 2026 | 06:05 PM

Joshinator99

Senior Member

Joined: Oct 2023

Posts: 472

Likes: 239

From: New Hampshire

ML 63 AMG

Quote:

Originally Posted by Samuelseggss;[url=tel:9250810

9250810[/url]]Hey everyone, I’m running into a recurring issue with my 2009 Mercedes ML63 AMG and could use some help.

Symptoms / What Happened:

I was getting P0191 Fuel Pressure Control: The Upper Limit Value is Reached.
After replacing the fuel pump, the error went away for about 2 days.
Now the code came back again.

Hi! I’m still fairly new to the ML63 myself and won’t be a ton of help, but will say our ‘09 is port injection only. There is no “high pressure” rail since that would be for direct injected engines only. So if you’re getting high pressure codes, it leads me to believe the ECM PWM control isn’t working for one reason or another. I’d hope that is something that could be seen with a good scan tool or Xentry. You should be able to see the ECM pulling back the pump output during times of low consumption (like idling for example).

Jan 5, 2026 | 06:33 PM

Samuelseggss

Thread Starter

Newbie

Joined: Jan 2026

Posts: 6

Likes: 1

2009 ML63

Thank you for your response,

I don't think i'm able to get such diagnotic tool at the moment, however. what else would you suggest i try.

Jan 5, 2026 | 07:52 PM

Joshinator99

Senior Member

Joined: Oct 2023

Posts: 472

Likes: 239

From: New Hampshire

ML 63 AMG

Quote:

Originally Posted by Samuelseggss;[url=tel:9250841

9250841]Thank you for your response,

I don't think i'm able to get such diagnotic tool at the moment, however. what else would you suggest i try.

Where are you located? Maybe there will a nearby MB World member with Xentry who can help. But I suspect you’ll need a decent scsn tool at the least. There are ok ones on Amazon for a couple hundred bucks that aren’t bad. The factory diagnostic software was cheap too (called WIS for Workshop Information System). Think I got a thumb drive from eBay for like $20 that had the MB WIS software on it. But you definitely want and need this if you’re going to own a Mercedes lol. Here is another place to get it: https://mbworld.org/forums/m-class-w...m_content=post

Last edited by Joshinator99; Jan 5, 2026 at 07:58 PM.