Hey all, I was driving along yesterday when all of a sudden I got the limp mode light and my car started lurching. I pulled over immediately and my car basically stalled (even though it's an auto). Checked the codes right away with my Foxwell code reader and got a bunch of different codes, but the most plausible ones are the "2BE9 Cylinder injection cutout: Pressure too low in high- pressure fuel system" and "2CO1 High pressure fuel, plausibility Pressure too low" (I also got a couple FRM codes but they don't appear to relate to this issue).

I've read a couple forums of this issue on here and on Reddit, and pretty much immediately found out that it's the HPFP - However, the weird part is that when I cold started my car this morning, I checked my fuel rail pressure and it was totally fine, 1200 psi on startup and 1700 psi while cruising. Others with HPFP issues seem to have persistent fuel rail pressure issues (at least until the engine warms up it seems), but mine seemed to go away. Anybody know what this could be, or experienced this same exact scenario to me? Is it possible that this could be a one time issue where the fuel pump just hiccupped?

Any help would be greatly appreciated!!

 

HPFP problems can be intermittent initially.

 

I just replaced mine. It was intermittent but it was definitely the HPFP
Easy to change just a really expensive part.
I think the word Mini is some sort of convoluted acronym for open your wallet and spend more money
:(

 

 

Something to consider, it could be the fuel pump relay. Mine was repaired by simply re-sodering the pins back on to the PCB.

 

Interesting... well I just overnighted an HPFP from FCP Euro and it should be here today (I'm also replacing my fuel filter). If that still doesn't do the trick I might see about this

 

Well I just installed a new fuel pump, fuel filter, and high pressure fuel line a few days ago, and everything seemed golden until about 30 minutes ago when I got the sudden limp mode and stalling again. Anybody know what it could be beyond all the stuff I just replaced? LPFP, injectors, HPFP relay... I'm really at a loss of words right now and have no idea what to look at next. If it helps anyone, I can see my fuel rail pressure dip into the 50 psi range on Torque Pro right as this happens.

Also, just to eliminate any possibilities, I've done all of this recently; timing chain, VANOS solenoids, pretty much every gasket on the car, oil changes every 3,000 miles.

 

Post the fault codes.

Can you still start the engine?

Does your scan tool also read pressure from the LPFP?

 

Here are most of the codes I'm getting (though I know most of them likely aren't related). I'm getting a few more codes than just these, but there's no way they're causing this.

C91E: Not present: No message (terminal status, 0x130), receiver JBE, transmitter CAS)
2BE9: Not present: Cylinder injection cutout: Pressure too low in high-pressure fuel system
2CO1: Not present: High pressure fuel, plausibility Pressure too low **This said "present" in the moment, but now that I've gone back it says "Not present"**
D35D: Not present: Message error CAS, receiver DSC, transmitter CAS
D377: Not present: DSC message: (PT_CAN_STAT_DS_VRFD, Identification Feature: 0x1E1) missing, receiver DCS, transmitter CAS
D35B: Not present: Message error CAS, receiver DSC, transmitter CAS
D517: Not present: No message (terminal status), receiver EPS, transmitter CAS
C994: Not present: No message (terminal status, 130h), SZL receiver, CAS transmitter
9CAB: Not present: FRM: One terminal 15 missing
E594: Present: No message (steering angle), receiver FRM, transmitter SZL,LWS,DSC

To answer your questions - my car starts up totally fine, and my scan tool doesn't appear to read LPFP pressure. Is it possible that I need to reset adaptations on the new HPFP or something like that (similar to how you reset VANOS adaptations after new solenoids)? And with all of these codes, it's almost got me a little worried that it's an FRM issue, which I've heard is not exactly cheap.

I would love it if my car could keep its hood closed and stay off the jackstands for quite awhile after all the service I've done at this point, but then again so does everyone else in this forum SMH...

 

After replacing the HPFP, the service manual states that the ECM memory must be reset. Do this and also clear all fault codes to see whether any fuel-related fault codes return.

 

Good to know - hadn't seen anyone talk about that on the forums or mention that in their vids. I'll try that tonight and see if it stalls again tomorrow

 

Do you know how to reset the ECM memory? I've been searching around for a while and haven't found anything. It seems there's a way to do it through the tachymeter on the R53, but that doesn't work on the R56. I saw a reddit thread where they did it with the Foxwell NT510 (same scanner I have), but they never actually said how to do it.

 

On my Launch scan tool, this is the command:
DME: Delete Adaptations

 

Alright, I think I found the way to do that on my scanner. I had to go through service functions/engine electronics/DME: Delete Adaptions and then it made me enter a new date, waited about 30 seconds and then it said it was finished. Hoping that was the right thing...

 

Sounds right. Also clear all codes to start fresh moving forward.

 

It's probably the fuel pump relay. I had the same issue.

 

Do you have a good way to fix that? I've been looking around for a quick fix, but it seems like I either need to tear apart my JBE or splice a bunch of wires in the kick panel fuse box.

 

This^ idea remains a possibility as a problem with the low-pressure side of the fuel system can't be ruled out at this point...
For example:

Code 2BE9



Code 2C01

 

Your recent stalling engine is consistent with the idea, but to properly verify, you would need to show that the stall was caused by a failure of the LPFP to run. Or if at some point, the engine cranks but won't start, the diagnosis could be made by showing that the LPFP doesn't run. Otherwise, you would need to remove the JBE, separate the two JBE boards, and then inspect the terminal 30G relay for a bad solder joint.

 

The way I repaired it was actually simple. I removed the fuse box and took out the module where the relay is solder to. It's actually 2 printed circuit boards stacked together. They are connected by pins that I carefully cut. You'll have plenty of room to cut these pins. Next I examined the relay and noticed that the solder joint was in bad shape which explained the internment running and not running of my car (heat caused the solder joint to fail, which is why the car ran fine when first starting). I re-soldered the pins on the relay and reassembled the two circuit boards by soldering the pins I had cut.

Here is a video showing basically what i did. Only difference was I didn't replace the relay. Just re-soldered it.

 

These^ CAS and FRM fault codes are also potentially consistent with a bad terminal 30G relay.

 

I just got back from two roughly 20-minute drives at a relatively consistent 40-50 mph where the car stayed at operating temp for about 30 total minutes, and no problems during that time. I've only reset the ECM memory so far, haven't touched the relay yet, but the car was noticeably better. Any chance it was just that? I know I'm reaching here and it likely is the relay at this point, but it would make me a lot more comfortable to do the relay as a precautionary step rather than a mandatory step.

Also, I've seen a method on here that some submarine electronics dude did that basically bypassed the relay altogether and used a 20 amp fuse in the kick panel instead. And another guy on youtube did something to tie the LPFP (video below) into the rear cig lighter. I'm liking these two options more because they completely bypass this JBE relay which just seems like an engineering fault more than anything. Any words of caution about either of these alt. methods or are they totally vaild? I'm aware that these methods mean the fuel pump will be on in accessory mode, but I don't sit in accessory mode hardly ever (unless I'm diagnosing).

 

Just informational...

One downside for bypassing rather than repairing or replacing a faulty terminal 30G relay is that the latter relay has multiple other functions besides supplying voltage to the LPFP relay. If you choose to bypass the terminal 30G relay, you will not regain its multiple other functions.

 

Hey fellas, it's come down to me replacing the relay at this point. Did the job, got the JBE reinstalled, car cranks but won't start. I'm now in the process of looking for a new board entirely. I hear people mention the "numbers" you have to look for that have to be the exact ones for it to work. My question is what numbers am I looking for? Is it the ones on the case that start with something like 61.35 34... and so on?

 

Does the LPFP fail to run when you crank the engine?