1999.0 A4 2.8 30V AHA

I have a few codes that an Audi, Merc, and BMW specialist hasn't come up with solutions for, but he was looking at the throttle body. The car is back at home for the time being. Any help is appreciated.



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Address 01: Engine Labels: 078-907-551-ACK.LBL
Controller: 4D0 907 551 AH
Component: 2.8L V6/5V MOTR HS D02
Coding: 06201
Shop #: WSC 06335
2 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
17956 - Boost Pressure Regulation Valve (N75): Open Circuit
P1548 - 35-00 - -
Readiness: 0110 1101

 

do AHA 2.8's have n75 valves?

 

I really don't want to face the stealership...

doesn't an n75 valve have to do with a turbo?

I should mention, holding the RPMs at a level higher than 1100 causes the engine's RPMs to meet wherever I'm holding it, drop down to near nothing, and pull back up as if it's revving on it's own. It feels as though I have 3 cylinders instead of 6--like the throttle isn't opening all the way

 

Yes, the N75 valve is part of the control system that regulates boost pressure. I can almost guarantee that a AHA 2.8 doesn't have one, but I'm not sure why else that code would be there?

I just did some googling and it seems that other code is a soft code (meaning that it doesn't throw a CEL) that comes from unplugging the battery. I also read several threads that linked this code to a bad ICM. Did AHA have an ICM?

 

The soft power code is referring to terminal 30 on the ignition switch - basically it saw a low voltage at the switched ignition output. It's a transient code and basically means nothing. Maybe you started the car once with climate control set to full blast, seat heaters on, stereo on, wipers on (you get the point), or the car bogged at some point, and it set the code. The n75 code does not apply to your car. I wonder if the guy dyslexed the code or if it was some freak thing. Clear them and see if anything comes back. Them you will know if you have to troubleshoot anything.

 

Back story...sorry I'm doing this in reverse. I drove the car from North Carolina to Mass for Christmas break. It drove like an Audi should and was fine. The inspection had run out and I needed to get that sticker up on the window before the RMV pulls my registration. Took it to a reputable shop to replace an O2 sensor and fix my passenger airbag which threw a code for "intermittent voltage." Those are fine now, but he wanted to make sure it would pass inspection before giving it back to me. He drove it on the highway doing a couple mile drives each way to get the readiness code. Instead the CEL came on and it started bucking.

As for the code..I pulled those myself with a cheap Vag Com cable. The guy said he wasn't sure if it was the throttle body or a wiring issue because it was previously in a crash and whoever "fixed" it, apparently "fixed" it something else.

I did unplug the battery for 2 hours, reconnected it, turned the key and listened for the throttle body to realign but heard a sort of clanking sound that lasted about a second as I was getting out of the car.

I'm hoping it was a freak thing and will get the codes cleared soon

 

are you sure you got p1548? that code definitely should not be showing up on a NA car. rescan the car. the bucking is from misfires. you should be getting misfire codes.

 

Not that I know what it feels or sounds in person to have a car misfire, but it definitely seemed like it was misfiring.

Though it's only a Ebay vagcom cable with VCDS* Lite, I scanned that, copied and pasted it here. Maybe the software is out of date, but I'll call the shop and ask specifically for the codes tomorrow.

Possible problems/hopeful solutions I have in mind are:

spark plugs
throttle body
throttle position sensor
ground wire short
cleaning the MAF really well (guy said he wiped it real quick but it looked clean enough...not so sure about that)

 

For anyone with a similar problem and to resolve this thread....

Had the car taken to the dealership today to get things straightened out. They are set on replacing the car computer for $1600. I plan on paying a friendly visit to the shop which had my car to replace the passenger airbag module and B1S2 O2 sensor. They seemed legit with new model Audis, Benz's, Volvos, etc in the garage. I find it strange that the computer would decide it's a 1.8T instead of a 2.8 while at their shop. Whatever software he used apparently didn't cooperate with my car, or he replaced the computer with another ?

The dealer is also set on charging $1400 to repair leaking brake lines/system.


I know Audi's are expensive to maintain, but is this is a reasonable price? I don't think so.

 

Too high, probably overkill as well. When you arent under warranty its a good idea to avoid the dealer generally IMO, you can find much better prices at other independent shops.