Hey guys,

Just purchased my A4 today with knowledge that the CEL has been on, but is apparently a fluctuating item. I figured that it must be a bad sensor somewhere if it is on and off frequently. I took it to Autozone to have them check it out and give me the codes. He briefed me a little bit, but was having a hard time figuring out what all of them were. If you could let me know what these are and what the seriousness of each one is, that would be Here they are:

P0150
P0174
P0401
P1101
P1106
P1250

Let me know what you guys come up with and I'll let you know what I was told. THANKS!!!

 

p is for powertrain

0150 is 02 sensor circuit malfuntion(pre-convertor sensor bank 2)
0174 is system too lean bank 2
0401 exaust gas recirculation flow excessive
1101 02 sensor low voltage (pre-convertor sensor, bank1
1106 02 sensor low voltage (pre-convertor sensor, bank2
1250 fuel level low

they all have to do with the same thing.
bad air fuel ratio.

401 is your egr valve. if its vacume opperated like i think it is and it says the flow is excessive. its eather stuck open or the vacuum line to it is not connected

and your if your 02 sensor is bad it will really jack up your air fuel mix. 02 sensors go for about 150 each and the egr is about 150 buy a aftermarket repair manual with a 97 with such high miles your gonna need it. and with the german parts i hope you bought it cheap and your wallets are deep. and get aquanted with your local salvage yard.

good luck maybe someone else can piece it togeather better than me

 

So, should I fix the EGR valve before bothering with the 02? If so, what should I do to try fixing/reconnecting it?

Also, I am just waiting for a little more cash to buy the manual. I just hopped over from Bimmerforums as I had a 325i and have been able to find EVERYTHING on there. I've been rather disappointed with the few DIY's that I've found for the A4. I'm giving it a little time, but we'll see. So far though, the people on the Audi forum are a lot more kind-spirited.

Let me know what I should do about the codes now that they are diagnosed. Thanks!

 

here is a pretty cool diy website for audis
http://www.audidiy.com/b5a4.html

the egr basically sucks air in the engine when its not getting enough its usally near the heads or intake manifold
they have electric operated ones too that use a silenoid to let the air in too.
but if its vacuum it will be a metal circle looking thing around the upper part of the engine connected streight to it. and it should have a vacuum line hooked up to it. if you find the egr but no line find the line and connect it. i have a 2000 it is commen for the vacuum lines to disenigrate on older cars i had to replace all of mine it would be a good idea to do that but not befor you fix this problem. dont want to spend a bunch of money and still have problems

and im not even sure this is your problem it could be your not getting the proper fuel and the air is fine. then you would be looking at your injectors and fuel dilivery system. but its better to check the easy stuff first.

your best bet is to get that manual asap. so at least it will help you in the locations of what you need to find. ill look on alldata later today for where it is

and yes i would check the egr befor i got the 02 sensors

 

hmmm many codes are a good sign and the P0401 which means the EGR system is the problem and would cause all the other codes,

P0401 = EGR system - insufficient flow detected and possible causes are hose leak/blocked, basic settings not carried out ( if applicable ), wiring, EGR valve, EGR solenoid, ECM im going for a blocked/leaking pipe/hose

 

16785 P0401 EGR flow insufficient detected

Look for vacuum leaks.

 

So the verdict is pretty much locating the problem within the EGR system, right? So, since I don't have a repair manual yet, can one of you guys point me to the location of the EGR and any of the vacuum hoses that could be leaking or blocked? If someone has a diagram, that would be extremely helpful. I can't really check it out unless I have some direction of where it is at.

I did google it, but only know what the system looks like now. I was unable to find any sites or images that gave away its location. I really appreciate the help. Thanks!

 

Check all the vacuum lines.

 

i looked on alldata and it is right under your plastic engine cover is, the part that says v6

 

So there is definitely a leak somewhere. It is an apparent little 'psssssss' noise. Assuming it is a hose...I spent about 20 minutes attempting to locate it exactly but did not have any luck. I had my hand up, down, and around the entire area but could not feel or find the leak anywhere. I am going to get a friend of mine to give me a hand with it and see if he can find it.

I'm not certain exactly what the vacuum hoses will look like. Are they the thinner ones that look like they are insulated by a shoelace? Or should they be exposed plastic or rubber? If somebody could get me a picture of an EGR on an A4 Quattro, that would be really helpful for me. Also, does anyone know, should the valve be mounted vertically or more on a horizontal axis (Just so I can make sure I'm dealing with the right piece)?

Thanks again! It's narrowed down now, it is just a matter of finding it...