View Full Version : 1999 A4 Problem

03-22-2016, 12:37 PM

How you all doin?

It's been awhile since I posted on this forum but a few questions I have about my son's 1999 A4 straight six...

It stopped on the highway the other day...no engine light no codes....he had it towed against my will but kids are kids and want things asap...Phew..

Problem...the dude he took it too somehow read a code and states it was the Crank Position sensor...which he changed out...but car will not start...

saying he needs a better OBD to scan...But my question is what makes that CPS go bad? timing issue and how?

And he says the mechanic that read another code stating something about the fuel flow sensor? wtf never heard of that...FFS

I had a TT 225Q for quite sometime and did all upgrades codes etc,. and I have never heard of a fuel flow sensor...

any help on this I would appreciate if not throwing codes and everything else checks out..battery etc,. not overheating...plugs are dry...turns but does not start..

getting fuel...

tuff one...

03-22-2016, 03:24 PM
Well im no expert but i had a similar issue. Also i dont know of any stock straight six a4. You either have an inline 4 1.8t or av6 2.8l. Unless someone gave that car a vr6 and somehow made it fit or something crazy.

Anyways my camshaft position sensor went bad and i had to change it. Its on the top front right of the engine looking at it from the front of the car. Easy to replace shouldnt be expensive. They are a small magnet. They fail wen they get wet. Or at least thats how mine failed. Mine turned. But did not know wen to trigger the spark because it dint know were the cam was if that makes sense.

As for your other issues with codes i have never heard of a fuel flow sensor but i have heard of fuel pressure regulators failing. They are on the fuel rail and typically the dyaphram rips or the vacuum hose on it turns out to be ripped. Mostly the ripped hose.

If none of this helps im sorry just trying to help from my personal experience owning and fixing audis.

Sent from my iPhone using Tapatalk

03-23-2016, 03:35 AM
Yep av6 2.8 i call all six cyl straight sixes old school I guess

Yes the dude changed the crank position sensor I will have him check the fuel pressure

I'm searching for the fuel pressure regulator now that I searched it..yes I remember I had changed mine twice on my TT

I may have him change the 02 sensors spark plugs and maybe the mass air flow sensor...

thanks a bunch

03-23-2016, 04:37 AM
I would leave the O2 sensors, spark plugs and MAF alone for the time being. None of these will stop the car on the freeway, and cause a none-start situation. Bad plugs would most likely cause a misfire long before they quit altogether, and would log codes.

If you're getting a fuel flow code (I'm not sure what that is), I would be looking at fuelling. You can log fuel pressure on the B6 A4, I don't think the B5 supports this. Something tells me you've got a fuel pump issue. So start from the basics.

Fuel pump fuse.
Fuel pump relay.
Fuel pump.

Crank with a good battery, pull out the plugs, and check for the presence of gasoline. Worth cracking the return line on the fuel rail. If there is gas, are the injectors pulsing? LED's will come in handy here. If the fuel rail is empty, start from the fuel pump fuse.

03-23-2016, 06:42 AM

Nice thanks....will do...