ppontes

Hi,

Just signed up in this forum, because I'm not able to find a solution for this.
I've read hundreds of posts regarding this issue, but after a while, there are so many different causes for this problem, that I got lost on the way to find the right solution.

I own a 1999 Audi A6 Avant, 4.2L, and approx 2 years ago, I got for the first time the ABS+ESP+Big red brake light on, all at the same time, follow by 3 beeps.

This has happen with the car cold, warm, running at 50km/h, running at 230Km/h, comes and go. The first time this happened I changed the ABS ECU unit, the MAF, but it didn't solved the problem. I never understood why, but after a while the same way the problem came, also went, and the car has been running for the last 2 years with out any problem.

Unfortunately the problem returned, and I want to understand what might be wrong this time.

When I connect the VCDS, I get these fault codes:

Chassis Type: 4B - Audi A6 C5
Scan: 01,02,03,06,08,15,16,17,18,22,34,35,36,37,45,55,56 ,57,65,67,75,76,77

-------------------------------------------------------------------------------
Address 01: Engine Labels: None
Controller: 4D0 907 558 A
Component: 4.2L V8/5V G 0002
Coding: 05752
Shop #: WSC 02325
VCID: 2B2984AFCA1D
1 Fault Found:
16487 - Mass Air Flow Sensor (G70): Signal too High
P0103 - 35-10 - - - Intermittent
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01V-927-156.LBL
Controller: 4B0 927 156 BA
Component: AG5 01L 4.2l5V RdW 1214
Coding: 00001
Shop #: WSC 02325
VCID: 67A1389F1675
1 Fault Found:
18265 - Load Signal: Error Message from ECU
P1857 - 35-10 - - - Intermittent

-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 8D0-907-389.LBL
Controller: 8D0 907 389 A
Component: ABS/ESP allrad D05
Coding: 06397
Shop #: WSC 02325
VCID: 311596C7E831
1 Fault Found:
18265 - Load Signal: Error Message from ECU
P1857 - 35-10 - - - Intermittent

Based on this input, could someone give me a hint on possible solutions?

Thank a lot.

indoor

Brake light switch is bad. A weird electrical issue causes these lights to come on when the brake light switch needs to be replaced...

devinsixtyseven

x2 brake light switch. It's inexpensive and easy, and should be an extra part in your toolbox along with a spare CTS.

Install, clear codes, see what comes back. Mine eventually threw an error specifically for the brake light switch, but sensors and switches can malfunction without being implausible or disconnected, as others have seen with the CTS. Mine also beeped and lit the dash like a Christmas tree, same as yours.

ppontes

Just an update on this topic.

As suggested:

• I've changed the brake switch and nothing changed.
• Checked the break fluid reservoir and replaced the brake fluid, and nothing changed.

Done based on Audi feedback:

• Replaced the ABS module and nothing changed.
• Replaced the Mass air flow sensor and nothing changed.

Done based on a suggestion given by mechanic:

• Remove the Intake manifold module, clean it and reinstall it, and guess what: problem solved.

Hope this can help other members experience the same problem.

jcman

What is a intake manifold module? Are you talking about the Crankcase Vent Valve??

indoor

Or intake manifold tunning valve? But that's electric right? Or at least on the 2.8L engine it is, so I don't know how you'd clean it

SloopJohnB@mac.com

What is this intake manifold module? Does it have an audi component number?

jcman

It's vacuum actuated on the 2.8 for the manifold change-over valve with exception to the electric solenoid valve that directs vacuum to the diaphragm actuator to rotate it in the manifold for a long or short path of air to the intake runners, any failure in this system would cause a slight engine performance deficit with no codes unless the spool seal is drawing air causing a vac leak, "rare".

SloopJohnB@mac.com

Agreed. I've had multiple audi intake manifold flapper/rod/vacuum motor and link failures with no codes. It's a miserable and expensive design to fix but not as bad as a transmission failure because Audi chooses to bigfoot ZF's transmission care recommendation.

jcman

Yep it's all down to the "Lifetime" fluid description without the small print disclaimer regarding the reality of wear and tear.