N276 Fault After New Intake Manifold Install

A6 All/ S6 All
#1

Hello.

I just replaced my intake manifold with a new one from JHM. That was last night. Car was running good; no problems. Drove the car to work, car still running good. Went to lunch, car starts running rough and EPC light is on. I scanned with VagCom and I get a N276 fault code, fuel pressure regulator valve. I have not had a chance to really investigate it further yet.

Anyone encounter this? I was careful in reassembling everything and I double checked all the connections. I don’t think any trash could have gotten into the system as I covered all the connections prevent this. Any suggestions on how to diagnose this or fix this are greatly appreciated.

Just in case, I ordered new high and low fuel pressure regulators. Going to check fuses this evening.

#2

Your pictures are really high quality… Probably some of the highest quality S6 ones I’ve seen yet! Couldn’t help but notice you removed the HPFP on the passenger side. I’d check measuring block 140 to see what’s going on with the fuel pressure (and then do the same for the other side just to compare). I believe around 40bar at idle should be good.

Also, in this picture ( https://photos.app.goo.gl/k44Tf7YSQ7ChiQeH8 ) I noticed the fuel supply lines leading into the fuel rails seem to not be seated correctly. Of course, this picture wasn’t taken when it was all finished up so you might have well have corrected it, but thought I’d mention it just in case as I could see it leading to a fuel delivery problem.

Engine bay looks clean as hell, BTW!

#3

Thanks for the suggestions. I am going to check fuel pressure, wiring, fuel lines, fuses, anything else I can think of. I will probably take off the passenger HPFP and check for debris in the fittings. I am hoping it is something simple. I highly doubt the HPFP would just all of a sudden go bad.

#4

The error code I get is P2294 which points to the HPFP. I was very careful in handling it so maybe it was already on its way out. Maybe removing and re-installing it pushed it over the edge?

I just read through the S6 Info Dump thread, and reading on page 12 a post by c.scot and my issue sounds exactly like a bad HPFP just like in that post. Reading in that post, it also looks like Audi made an updated HPFP.

Sigh, so I am going to order 2 replacement pumps. Oh, well.

I took the pump off and there is no obvious problem with it. Cam follower and cam lobe look good. I checked all the electrical connectors and wires and they all look good too.

I also decided to take the intake manifold back off to make sure the wires for the high pressure fuel sensor under the manifold on the fuel raid was okay. Looked fine. I have one on order so I will change that just in case also.

#5

Update. 99% sure I figured out what the problem is. It is the drivers side HPFP, the one I did not remove from the engine.

I checked the Bentley manual for diagnosing the HPFP’s (and any other possibilities for my problem). It says to check the terminals of the HPFP fuel metering valves; the terminals should give a resistance of 450 to 1000 Ohms.

Passenger Side = 292 Ohms. (out of range)
Drivers Side = 1.5 Ohms. (basically shorted out)

I still had the Drivers Side pump on the engine and had to remove it to check the terminals. And as I removed it, I could see that there was a very small crack on the edge of the plastic. More than likely I bumped it the last time I removed/installed the manifold. The plastic on these HPFP metering valves is very fragile, probably more so from the last 10 years of under hood heat. You can find lots of pictures on the internet of cracked or broken ones.

It is probably a good thing to change the pumps regardless. The passenger side pump looks like it was weak and on its way out anyway as it was out of range.

Should get the two new pumps from JHM later this week.

I have added pictures of the fault code in VCDS and a picture of the crack on the HPFP plastic to my Google album.

https://photos.app.goo.gl/SrSuEE9KxSz3RECk6

#6

WOW that sucks. So you only were able to find this out by putting a voltage test to it.

I can never see any of the pictures. It just goes to a blank screen.

#7

Yeah, sucks but it is what it is. At least I will not have to worry about the pumps again. More than likely I bumped the driver’s side pump when installing the manifold but I don’t think it took much to force to crack it. Like a lot of the plastic parts under the hood, they are brittle from the heat (more so actually). I actually couldn’t even see the crack until I looked really closely at it. The passenger side pump probably doesn’t have much life left in it as it was reading only 292 Ohms and the specified range is 450 to 1000.

Actually, it isn’t the pumps that are the issue a lot of the time. It is the N276 fuel metering valve on them. But as far as I can tell, you cannot buy this part separately.

Not sure why you can’t see the pictures. Maybe try a different browser?

#8

UPDATE 6-28-2018

So I received the two new HPFP’s from JHM yesterday and installed them. Car is now running. When reading measuring block 140 in VagCom the commanded fuel pressure is being given, 35 bar.

Side Note: I think the Bentley manual is wrong on diagnosing a bad N276 Fuel Metering Valve. In parts diagrams, the passenger side pump is referred to as the N290 and the drivers side is the N402. Bentley manuals states that there should be a resistance reading of between 450 and 1000 Ohms when testing the two terminals of the connector on the pump. Both the new pumps from JHM, read about 1.5 Ohms and they work like they are supposed to. So I think my bad pump actually was the passenger side pump as it read 292 Ohms.

I also found some information taken from a repair manual for an RS4 that also uses two HPFP’s. They are referred to as the N290 and N402 and that manuals says the resistance reading should be between 1.5 and 11 Ohms. I think this is correct.

So now that I got the fuel pressure sorted out, I of course have a new problem although one that is not as serious I think. I am now getting a P2006 code; Intake Manifold Runner Control Stuck Closed, Bank 1.

I will make a new post to talk about that.

#9

Check one more thing off the list of small but nagging issues. Its good to see your checking them all off the list.

#10

Seems to be a game of Whack-A-Mole!

But it is a learning process. I am learning A LOT!