How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask AudiDoc Your Own Question
AudiDoc
AudiDoc, Independent Audi Shop Owner
Category: Audi
Satisfied Customers: 1695
Experience:  I've been working on Audis since I was 18 and own an independent Audi repair and performance shop
14582033
Type Your Audi Question Here...
AudiDoc is online now
A new question is answered every 9 seconds

I have a 99 a4 1.8t with the CEL light on for a while now

Customer Question

i have a 99 a4 1.8t with the CEL light on for a while now can not read any DCT'S no link at diag port have unplugged most modules and still can not link even with VAG scanner just want to know what all modules could cause loss of canbus. i have disconnected radio abs and ac head unit it is a 5 speed so it should not have a trans module just dont know where to go from here
JA: Does the light stay on, or does it blink?
Customer: it has been on solid for 4 months have changed almost every sensor on the engine and throttle body last week it has 4 new coil packs and plugs also both 02 sensors maf
JA: Are you fixing your A4 yourself? What have you tried so far?
Customer: yes i have been a service tech for the last 22 years with out being able to see what the problem i have replaced almost every engine sensor and still can not get the light to go off
JA: OK. To minimize me, please click the down arrow at the top right corner of this box.
Customer: all i would like to know is where all the modules are in this car so i can disconnect them one by one until i find the one that is taking down the canbus it is a 1999 Audi A4 Base 1.8T five speed the car was built in 1 of 1999
JA: Anything else you want the mechanic to know before I connect you?
Customer: not that i know of
Submitted: 8 months ago.
Category: Audi
Expert:  Wolfgang replied 8 months ago.

Thanks for choosing Just Answer . I'm Wolfgang here to help!!

I am confident we can resolve your problem together. Please
understand that I don't know your skill level. In most cases when you have a problem
with the way the vehicle performs, specialized tooling is required to acquire computer
data/information or engine testing results. We didn’t build these complicated vehicles; we
just diagnose and fix them. Also understand that I can't see, smell, hear, or touch the
vehicle either, so it may take a few replies to get to satisfactory results. Note there may be an issue where the complexity of the issue will require a Premium Service. This service will be an addition to the normal question cost. Usually it does not come down to this but keep in mind!! I am also going to direct you with the fastest, easiest and most common things to check first. Please be
patient and permit me to do what I do best.
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
through it.

NOTE YOUR DEPOSIT DOES NOT CREDIT ME FOR THE QUESTION AT HAND SO AFTER WE GET TO A HAPPY MEDIUM A POSITIVE RATING IS NEEDED SO I CAN GET CREDIT IN HELPING YOU!!
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail.

SO YOU DO HAVE VAG COM? IF SO WHAT HAPPENS WHEN YOU PLUG THE CABLE TO THE CAR DOES THE LED SHOW RED OR GREEN?

ANY AFTER MARKET STEREO OR EQUIPMENT INSTALLED IN THE VEHICLE?

PLEASE LET ME KNOW!!

THANKS