2007 Audi Q7 V6:
I replaced the brake light switch 2 weeks ago. Brake lights work fine, but a couple of days later I have an EPC warning light on the dash and the engine is not responding as it should. Then the car occasionally will not let the key out of the ignition after I park and turn off the ignition.
I broke down and purchased the VCDS connector and software this week (thank you Ross-Tech for the speedy delivery).
I take a read with the auto-scan and its telling me:
Fault found:
001393 - Brake Switch (F)
P0571 - 008 - Implausible signal

This shows up in the engine and transmission section.
In the Acc/Start Auth. section:
Fault Found:
00230 - Transmission Park Selector Switch (F305)
010 - Open or Short to Plus - Intermittent

I also have a scattering of Supply voltage and under voltage errors, but I'm sure they are due to the brake lights staying on all night and running the battery down.

I clear all the codes, and everything runs great. I drive a couple of miles down the road and after multiple applications of the brake, the EPC light comes on (I know what the problem is this time). At the end of the day, after getting in and out of the car multiple times with no issues with the ignition key, the ignition key will not come out. Luckily it waited until I was parked in my garage for this to happen.
I take a read on the error codes this morning and same 2 DTC's, brake implausible and park selector.
Obviously there is an intermittent problem with the brake lights and possibly one with the park selector micro switches. I haven’t had a chance to get under the dash and check all the connections for the brake light switch.
Has anyone had an issue with a brand new switch giving an intermittent issue like this?
Also, could the error with the switch cause the ECU to freak out enough to think the park selector switches are faulty or due I need to assume these are faulty and go ahead and plan on replacing them?
Your inputs would be greatly appreciated.

 

I have an A4 2.0 (2007) that has the same light on the dash and the brakes light stay on when started. I have had shifting problem at first that it shift ok first two time in at first start up. I have not bought a ross tech cable but am close.
it goes into the shop Monday to get it looked at and fixed.
will let you know what I find out.

 

I have the exact same issue. I just PM'd you. Not sure if you get emails so I am leaving a message here. Is this a faulty brake switch? I have solid on brake light and no response when pressing the brake pedal and the fault throws three codes. Engine, ABS and Auto Trans.

 

...turned out to just be the brake switch! 12 dollars on amazon*
I bought a different german brand than OEM. The OEM seems to be designed to fail. Multiple systems literally come down to a millimeter thin piece of copper contact that flexes every time you push the pedal and the metal itself if examined will reveal cross hatch pattern almost like scoring marks running perpendicular to the bend which would just be asking for the part to break off or weaken causing loss of contact at some point. Very poorly designed and definite deliberate planned obsolescence. I hate seeing weak things like that. Disappointment Audi. Giving consumers their planned to fail vehicles. Garbage.

 

Guys, I am getting the same problem and plan to buy a new switch tomorrow. Don't really have time to order so getting from Audi. Still far cheaper than taking it anywhere. Will post results and have fingers crossed