Audi A6 2.7tdi glowplug light flashing/limp mode

[gringosmith]

All was going well with my Audi A6 2008 2.7tdi Manual Estate until it stopped suddenly back in April. Diagnostics showed "Crankshaft Position Sensor Fault", however changing this did not get my car started, and two garages including an independent Audi specialist gave up on the car. The fault was finally traced to a damaged tooth on the flywheel caused by a piece of metal coming away from the clutch plate. One new dual mass flywheel and clutch later the car was up and running again, however.......

The glow plug light started flashing, and the car went into limp mode as soon as I went over 2,500 - 3,000 revs or so. The diagnostic report shows "004195 - Fuel Pressure Regulation P1063 - 001 - Control Range Not Reached - Intermittent". See log:

004195 - Fuel Pressure Regulation
P1063 - 001 - Control Range Not Reached - Intermittent
Freeze Frame:
Fault Status: 00110001
Fault Priority: 0
Fault Frequency: 8
Reset counter: 255
Mileage: 121992 km
Time Indication: 0
Date: 2007.10.25
Time: 09:47:04

Freeze Frame:
RPM: 3717 /min
Torque: 374.4 Nm
(no units): 5.0
Voltage: 13.53 V
Pressure: 1178.6 bar
Duty Cycle: 53.3 %

No other faults are present, and turning ignition off and on clears the fault until next time 2500 - 3000 revs.

I have changed the fuel filter, changed the valve on top of the fuel filter, tried a new air mass meter, removed the injectors and had them all tested by a reliable person, checked for any leaks in the fuel lines etc., changed the brake pedal switch (and clutch pedal).

When the previous garages were trying to resolve the crankshaft position fault, they tried fitting a new high pressure pump (then removed when it made no difference), and removed the ECU and had that tested. Somewhere in all of this I think one of them has caused this problem as it was not there before. As the car still runs, I have tried replacing the various parts mentioned over the last 6 months, but I would like my full power back....................Any ideas?

[MarkTM]

Is yours a kosher VCDS, reason I ask is the date of the fault shown as 2007. prior to your car being made!

Also if it's diagnosing a FPR fault have you thought to change?

Genuine pressure-relief valve Audi A3 A4 A5 A6 Q5 Q7 TT | eBay

I've googled (you can do the same)

It throws up:

Fuel filter
Leaking injector
Bad fuel pump
FPR gone bad

PS: Using the measuring blocks in VCDS you can check the fuel usage against what's being requested, but once again google would have given you that answer (and how to do it) too.

[Advanced-Tuning]

I would swap the rail sensor out if it was me, seeing you have changed the fuel filter already. The code suggests its not making the required fuel pressure

I am also extremely sceptical of ECU testing complanies. There isn't anything they can really test on that EDC16/17 ecu off the car,

Also remove the ecu plugs and check they haven't bent any pins

[gringosmith]

Thanks for your inputs. The 2007 date on the log is just because the battery must have been disconnected when the guys were working on the car, so that's an easy setup function to correct - done.

I have googled and read virtually everything on this fault code, on UK sites as well as European & US, but have not found a definitive answer. I am sure this is something silly, that one of the (so-called) mechanics has messed up, but I am trying to work logically and methodically through the process without throwing excess parts and money at the car.

I have ordered a Fuel Pressure Regulator Valve, and will also try to work out which VCDS measuring block codes monitor fuel rail pressure; actual v required.

I appreciate your comments and assistance - thank you.

Will update when progress made.

[Advanced-Tuning]

Fpr valve is different from the fpr sensor i suggested

[gupsterg]

gringosmith,

Not that I know how to fix you car, just thought you may wanna ref this info to aid you DIY diagnosis.

First google SSP 350, ref pages 26 & 27, this will give you overview of injection system.

Next google SSP 351, this will not get you right file but download first hit, page 30 & 31 cover N290 fuel metering valve. The fuel pump diagrams are for later 3.0 TDi (09-11) but info is relevant. The N290 on your fuel pump will be on rear, not top at a side. Page 33 covers G247 fuel pressure sensor, pages 34 & 35 cover N276 fuel pressure regulating valve.

Read thoroughly take note of functions, effects of failure.

If you have to change N290, Audi dealer will be with complete fuel pump but you can get new genuine via another route, read this post. Also that thread has measuring blocks info, even if its A4 3.0TDi info is same.

I'd probably set up MVB 01 , 22 , & 23 to view, IIRC 22 gives you activation of N276 in data window 4, 23 gives you activation of N290 in data window 4.

I'd also run a output test in module 01, this will test electrical response to ECU signal for N276 & N290, if you remove those sensors and VCDS is running output test you'll see if they are responding mechanically. Output text is run engine off.
I'll PM you some links, one of them has test for N276 when engine at idle to see if leaky fuel=loss of pressure in rail. If you want SSP 351 request via PM as online can only see German version and not English.

This may also be handy, item 2 = N276, item 3 = G247, item Link:- AUDI A6/AVANT [A6] (EUROPE) 2008: ENGINE: 13070. FUEL RAIL; INJECTOR UNIT; PRESSURE PIPES

[gringosmith]

Many thanks for all this useful info - especially the measurement codes to run.

I'll try these as soon as I have some time and give you feedback.

[gringosmith]

Audi A6 2.7tdi glowplug light flashing/limp mode - RESOLVED

Yes I know it's taken a long time but the car has been drivable despite the fuel pressure problem, and I don't want to be without car for my business.

So the I had previously changed the fuel filter, changed the valve on top of the fuel filter, tried a new air mass meter, removed the injectors and had them all tested by a reliable person, checked for any leaks in the fuel lines etc., changed the brake pedal switch (and clutch pedal switch).

Finally a week ago when the car was being serviced I had my mate fit the new fuel pressure relief valve which I bought a good few months ago. Picked the car up and gave it some welly and low and behold there was no longer the annoying glowplug light, or limp mode, despite trying my hardest with my right foot to trigger the sensor.

So I am guessing that the fuel pressure relief valve was fine at retaining pressure at 10 bar when the engine was stopped, but when accelerating heavily, it was letting fuel pass through slightly; enough to trigger the fuel pressure fault.

Thanks for everyone's input, and I hope in posting this solution, it may help someone else with the same problem.

All the best, Neal

[kimlk]

Eh.. Never mind. Brainfart and "quick reply"..
Did you ever resolve this? I just got the same fault code in my A6.

[gringosmith]

Yes, all resolved with a Fuel Pressure Relief Valve bought from Germany or Poland online (I forget which).

Are your fault codes and readings similar to mine? Is it only when you accelerate hard, and when the engine has warmed up a little?