P0191 fuel rail - OBD Fusion

Pfmilligan

New member
2014
V6

I’ve had my sprinter for about 4 months...$3000 into the DEF system and now I’m getting a whole new set of problems. I don’t even know where to begin to find the fuel rail pressure sensor.
Obviously I should have already gotten the workshop manual but here I am, almost broke with not enough sprinter knowledge to figure it out. Anyone with pictures or diagrams of under the hood? PLEASE!! In Taos, NM with little trust for local mechanics...
 

Pfmilligan

New member
You are a saint and a scholar! Thank you so much! I’ve been looking for that link all over the place. I’m sure it was right under my nose but… The credit goes to you!
 

manwithgun

Unknown member
Thanks should go to “showkey” who shared the link in another post. And an honorable mention to autostaretx and sikwan for helping integrate the Apple image format. I’m just grateful to have this forum and a community that shares information.
 

showkey

Well-known member
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JV33

New member
So I’m curious, did you remove the passenger side sensor on the rear of the fuel rail? And did that at the end of the day fix the issue? And can you remove the sensor while the fuel rail is on or do you need to remove the rail and re move the sensor while it’s off the van? If anyone can help on the second part. Please and thank you ����. Also installment is tighten to 60nm, back it off 90 degrees, then tighten again to 80 Nm??? Is this what everyone has?
 
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I recently diagnosed one with the same code. It was showing 1000 psi fuel pressure with engine off (should be 100 psi). Symptoms were long crank time and stalling. During inspection with the key still on I wiggled the connector at the fuel pressure sensor and I could hear the turbo actuator move around. Cleaned and tightened the contacts and the fuel pressure sensor started reading correctly. So rule out the connector before replacing any parts! I will be getting a new connector and will post the part numbers once the parts department finds it for me- unless someone else already has it...???
 
Sorry to dig up an old thread... but my check engine light came on today with the same P0191 code. Wondering... What are the chances it could it be as simple as a clogged filter.
 
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Just to report back... I replaced the filter and still have the same issue with a rough idle and occasional stall-out. But I do have the peace of mind of knowing I have a good fuel filter. I had not had codes from Feb. 7 through today. But, alas, the check engine light lit once again today. I received two gifts this time... The first was a P2195. The second code was, my previous, P0191.


Codes

P2195 - Code P2195 is an indication that the ECM is getting a signal to go lean from the O2 sensor and has tried to lean out the mixture to its limit and the system is still too rich. Common fixes include:


P0191 - "Indicates that the fuel rail pressure sensor is receiving a signal that is outside of its normal range. This is a generic code, which indicates that it has the same meaning for the Sprinter as it would any other vehicle. It is typically caused by a bad fuel pressure sensor, fuel pressure regulator, or an issue with the fuel rail pressure sensor wiring harness."


Plan of Attack:

First thing I'll do is remove the electrical connectors to the Fuel Pressure Regulator at the front of the driver-side fuel rail, clean them up, re-spring them to be sure they are making good contact, apply some dielectric grease, and reconnect.

Second thing I'll do (if the first does not fix the issue) is replace the fuel pressure regulator. Not quite as simple as it may seem since Mercedes only wants to sell the regulator and fuel rail together as a unit. Can anyone confirm that the "correct" part number for purchasing the regulator by itself is Bosh P/N: 6480700046 / 0281002682 ?? Also, what is the danger in replacing just the regulator for $250 instead of replacing the entire fuel rail for $1100+?


Third thing I'll (cry and) do is replace the fuel pump also for another $850+.
 
Follow-up --
I have received a replacement driver-side fuel rail (which comes with the fuel pressure regulator attached) from Mercedes Benz. Here are a couple close-up pictures of part numbers, for anyone who would attempt just replacing the regulator. Just to point out, my replacement rail came with Mercedes P/N A6420700246 / 0281002987 as the diesel fuel pressure regulator. ...And, although I ordered it from Amazon, the MB Dealer in New Jersey, who actually sold me the part, called me to ask the last numbers of the VIN so he could verify the part was right before he shipped it out.
 

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