I pulled codes and the transmission is throwing no codes. the engine had one code. i dont remember the exact code but it was something to do with a brake switch. (my esp comes on once in a while and does not turn off until car is restarted)

so anyways im driving the car IN TIPTRONIC and suddenly the car has a huge jerk and a big thud sound. i look at my info screen and im in 4th gear. i put it back in 5th and no problem. then again i was going around 40 same thing but less jerk and a softer thud because it was slower.

the car goes into fifth but JUST SOMETIMES goes to 4th but i am able to put it back into 5th. the shifts are smooth and fluid is OK i got it changed 6000 miles back.

btw my a6 is a 2002 2.7t if anyone can tell me the answer that would be great. also there is no check engine. but there was that brake switch code in the ecu stored. mechanic said the ecu has to throw the code 3 times in a single ignition to throw a MIL. but anyways someone please help me

 

I don't think the brake light switch would cause the condition you are describing. I also don't think you are going into limp mode. Limp mode would put you in third and all of your gear indicators would light up.

To me, it sounds like you have a sensor that is not working properly somewhere. Not sure if is a transmission sensor or an engine speed sensor but the way you describe the downshift, it sounds like your car "thinks" 5th gear is too high for the speed you are traveling. Or maybe something in the TCU has gone "wonky". Have you tried a reset?

 

yes i disconnected the NEG terminal over night and pluged it back in and the TB adapt and all that. and just now i took out all the fuses that had to do with engine control unit and put them back. at one fuse the PRNDS light up and i put the fuse back in and it was gone. shoudl i disconnect both terminals?

if i had a sensor problem it should have thrown a code right? the code was read by a european specialist so it wasnt a cheap auto zone code reader.

so lets say it was a speed sensor, how hard is it to replace them? how many sensors would i need to replace? do u have any idea how much each sensor would cost Apprx.

 

oh and this started happening the day after i put the progressive snap snot thing in the diagnostic plug. anyone think this could be causing the problem?