Hey guys, need some help. Ford s max 2015 2.0 dieselstarted running rough out of nowhere ,throwing engine light p0251.p06DB,p0380,

I did replace the fuel rail pressure (FRP) sensor too, but I’ve checked all the wiring, replaced glowing relay did software update on PCM bcm done reset on everything checked Ecu wiring so far and it’s throwing a short to ground code—except I can’t find any actual short to ground anywhere.I also checked the high-pressure fuel pump sensor, and it’s working fine. Did a leak test on the injectors, and they’re not leaking. The car was running smooth before, but after swapping the pipe, this issue popped up.

The fault won’t clear, so I checked the fuses—both in the BCM (Body Control Module) fuse box and the engine bay fuse box—and they’re all good.Since the fault still won’t clear, I’m starting to think there’s something deeper going on. Maybe an issue with the wiring somewhere I haven’t checked,

Anyone have ideas on where to look next? Could this be a grounding issue elsewhere, or maybe a problem with the sensor itself

Unless, as you say It is shorting inside the actuator (disconnect and test, applying heating and vibration?)

All the diagnostic guys I follow would then investigate the wiring from the actuator on HP pump to PCM?

That code seems to clearly indicate a short to ground so with my limited knowledge I'd look for damage to the loom where it changes direction, rubbing on bodywork etc. 

If  nothing obvious found then it must (AFAIK) be a short to a ground wire inside the loom?

Obviously, if short to ground, the solenoid won't get the right signal which does match your symptoms?

6 hours ago, World technology uk said:

The car was running smooth before, but after swapping the pipe, this issue popped up.

That to me would be a big clue as to where to start looking.

8 hours ago, Shearers said:

Unless, as you say It is shorting inside the actuator (disconnect and test, applying heating and vibration?)

All the diagnostic guys I follow would then investigate the wiring from the actuator on HP pump to PCM?

That code seems to clearly indicate a short to ground so with my limited knowledge I'd look for damage to the loom where it changes direction, rubbing on bodywork etc. 

If  nothing obvious found then it must (AFAIK) be a short to a ground wire inside the loom?

Obviously, if short to ground, the solenoid won't get the right signal which does match your symptoms?

Thank you for your reply. I tested the plugs with a multimeter on the HPFP sensor solenoid, and the voltage fluctuated around 5.61V—going up and down. I disconnected the plug and wiggled the wires, but the reading remained the same,when I disconnected the plug leading to the wiper up to the coolant tank, the voltage stayed stable. However, the trouble code won’t clear, and whether the plug is connected or not, the engine continues to vibrate and run roughly.

 

The engine and wiring loom have already been replaced, yet the issue persists. The original engine experienced the same problem, so I initially suspected the PCM and replaced it, but that did not resolve the issue. Perhaps we should consider inspecting the BDCM or further evaluating the wiring harness.🧐

3 hours ago, unofix said:

That to me would be a big clue as to where to start looking.

Well go on shot your guess ,you might have better views 😁

The voltage signal to that solenoid is PWM i.e. a square wave with variable mark/space ratio (if I have the terminology correct) therefore a straight multimeter voltage reading won't mean much.
It needs an oscilloscope on it to see what is going on - if the signal is erratic that will allow fuel rail pressure to be all over the place - have demanded and actual rail pressures been monitored?
Plus other confusions (to me):
What pipe was replaced that "caused" the problem?
Was it an "old" wiring loom (with all of the risks that entails) and was the fault present before that was changed plus why was all that work necessary (for background and getting clues and the full story)?

Has the "new" or old engine ever run correctly since it was fitted - you seem to imply that this fault has carried over from an engine and wiring harness change which may mean it is something else that hasn't been changed but PCM has also been changed so was the loom from PCM to engine completely changed or only part of it?
"Vibrate and run roughly": regular, one cylinder (loosen fuel pipe?) or random multiple cylinders (back to fuel supply or something we don't know about yet?

Fuel filter changed (always the first thing to do IMHO and check for any bubbles in the fuel line (second thing to do)?

P06DB is this crappy engine oil solenoid that appears to cause all sorts of trouble - so that needs checking?
P0380 is glowplug related - more possible trouble at some point if either are still present (which they are on your original screenshot?)

As usual, that's my best, sorry if I'm missing or duplicating!

I measured the rail pressure sensor, and it’s reading around 5V. Essentially, the garage replaced the engine along with the wiring loom because they suspected the engine was faulty, they couldn’t pinpoint the real issue. They installed a new engine, which ran smoothly at first but soon began running rough again. They kept swapping parts without properly investigating the actual problem, and eventually, they called me in to check it. Now, it turns out the replaced engine was fine; the issue lies with another component in the car.

 

I’m leaning toward a fuel pump issue because I’ve read a few threads where replacing the fuel pump cleared a similar code. An injector problem seems unlikely since the car ran smoothly initially. I even installed a new PCM to see if the voltage or fault code would change, but the fault code (P06BD) (p0251)( remained. I connected the PCM plug without programming or starting the car, reasoning that if the PCM were at fault, the code would clear with a different PCM—but it didn’t. Additionally, the wiring loom was completely replaced (the new engine came with one), and the fuel filter was also replaced.

 

Despite these changes, the P0251 code persists.p06DB even though it has new oil and the solenoid is clean, yet the car continues to run roughly and misfire. I plan to disconnect the plug to see if the codes clear.🧐 Although the glow plug module has been replaced, I’ll also replace the actual glow plugs to eliminate that possibility.

 

Thank you for helping narrow down the possibilities and making the discussion easier.

Thanks for coming back and explaining.

With all of that (expensive sounding) work being done (changing an engine because they "suspected" is a worry to me!!!) I'd really take a deep breath and try to look at some serious diagnostics to ensure any parts changed are actually faulty.

Pump:

Again, the 5V measured on rail pressure sensor will likely be the supply (there's 5V supply, earth and signal which varies but not from zero as that would fool us into thinking it was OK)

Again, if you are suspecting pump, I still say Forscan or other could be used to see demanded and actual fuel rail pressures. to try and rule that out - if pump can't supply then it's either fuel starvation, air leak, cracked filter housing, a dodgy pump, I am told the springs can break inside or...? You also have a spare (N.B. The pump need to be timed - there are marks, see Alan Howatt on You Tube)

AND if it's a single cylinder fault then prepare for fuel spillage by loosening rail pipe OR disconnecting injector lead at each might narrow that down?
Test the glowplugs with a multimeter for resistance  or clamp on meter for total or individual current as AFAIK it's not an easy job requiring EGR removal (on my engine)

I know I'm repeating but, to me, these simple checks and further diagnosis (like finding a specialist with a pressure sensor that can confirm rail pressures for example) saves all the time, effort and expense of changing parts.
I'll post below some of my fave guys (where are the Girls!) and their methods are very valuable (I'm trying to encourage testing not guessing):
The Masterful Diagnose Dan:
https://www.youtube.com/@Diagnosedan

Jimmy (DPF specialist):
https://www.youtube.com/@ORileysAutos

Our local Master:
https://www.youtube.com/@intelligentauto737

Skoda Yoda:
https://www.youtube.com/@SYDiagnostics
 

And a newcomer:

https://www.youtube.com/@mrautoservices7354

Your choice on how to proceed, of course!