Thread: 2011 D4 'Gearbox Fault' warning

Thanks. I finally got around to watching the vid. It was very helpful.

Originally Posted by BradC

If you can find a new one (not a refurb) for less than $2.5k now, grab it and run.

Jefferson Ford here in Melbourne they are $2200.

Originally Posted by loanrangie

Jefferson Ford here in Melbourne they are $2200.

I did try them and was on back order in fact the one I bought was reselling Jefferson Ford parts



Bought off below who I found via EBay. $2200 plus $30 delivery was relieved when it got to my doorstep.

Very helpful. Thanks.

Alrighty...things have taken a bit of a turn today and I've got codes galore.

I usually fill up at our local 7-11 and in the last 1/3 or so of the last tank the car has been driving to and from work quite well with almost no surging. I was kidding myself that perhaps I had a blocked injector or something that had miraculously cleared - if that is even a thing. On Sunday at about 1/4 tank I filled up at a Shell and within about a minute I was getting the familiar surges again.

At about 10 am today I got a Gearbox Fault / Restricted Performance. I scanned with my iCarsoft and saw 3 codes I had not seen before: P2290 "injector control pressure too low' and P0730 "Incorrect gear ratio" and P0191 "Fuel rail pressure sensor range/performance" and the familiar U2023 "Fault received from external node"

I get back to work to see my shiny new GAP iiD G3 had arrived from British Offroad in QLD (paid yesterday arrived in Sydney today) . So at lunch I plug it in and have a play so I can watch some snappy graphs on the way home. And what timing.

Right at the first incline where I usually get some tacho needle bouncing and surging I get the first Gearbox Fault / Restricted Performance. So I scan with the GAP and I get:

P0087-00 (2F) Fuel rail/system pressure - too low (first time I have seen this one)
U2023-86 (2F) Control module network signal calibration data - Bus signal/message failure - signal is invalid

Just up the road driving normally on the first gear change I get:

P117D-00 (6C) Fuel volume regulator control exceeded maximum control limit
U2023-86 (2E) Control module network signal calibration data - Bus signal/message failure - signal is invalid


A bit further up another hill (same codes):

P117D-00 (6C) Fuel volume regulator control exceeded maximum control limit
U2023-86 (2E) Control module network signal calibration data - Bus signal/message failure - signal is invalid

At this stage I started crawling but got a bit careless on the pedal and instantly got this for a bit of a variety:


P2290-00 (2F) Injector control pressure too low (first time I have seen this one)
U2023-86 (2F) Control module network signal calibration data - Bus signal/message failure - signal is invalid

I was really careful but had another hill to climb and I got:


P2290-00 (2F) Injector control pressure too low
U2023-86 (2F) Control module network signal calibration data - Bus signal/message failure - signal is invalid

So now I'm pretty sold on the fuel angle. I have a new fuel filter and was planning to change it this weekend and test the LPFP for correct operation and perhaps drop and drain the fuel tank to rule those out.

Should I just accept the HPFP diagnosis? Or should I still go fishing for a blockage somewhere? With that run of limp modes the car is on holiday now anyway.

Get a pressure gauge on the fuel feed schraeder, cable tie it to a windscreen wiper arm so you can see it from the drivers position and go for a drive. That will rule out both your LPFP & fuel filter in one hit. I had no issue driving around with the LPFP fuse out entirely. The feed pump in the HPFP will suck a golf ball through a straw, The issue is the pressure drop in the fuel system will boil the diesel under low pressure and the cavitation will destroy the feed pump, which then sends debris into the valves & high pressure pump.

So you need the LPFP to stop the HPFP lunching itself. It us also necessary to operate the jet ejector in the fuel tank that makes sure fuel is pumped uphill on a low tank and high grade descent (nose down).

A pressure gauge will allow you to rule out the entire system south of the HPFP assembly in one drive, as long as the fault occurs on that drive. Just watch the pressure. If it dips when it faults then suspect something else. If (as in my case) the pressure remains steady, in whatever that is at the time then it's the HPFP.

P0730 incorrect gear ratio is definitely trans related and not a cause of the HPFP so you likely have 2 issues going on here.

Thanks again guys.

My unqualified spider sense agrees. I'm still pretty suss on the solenoids in the control module since I'd say at least 90% of the faults seem to occur on a gear change. But I really don't have anything to back up my suspicions. Dr Google seems to suggest P0703 indicated issues with solenoids and/or TC.

I'll get the LPFP checks done and change the filter this weekend so at very least I can check those off. Testing and cleaning the injectors is also on my list, but I could probably park that for now.