Help diagnosing possible gearbox issue.....

[Fil3807]

Hi All...

My C5 RS6 has developed a gearbox fault.

First off the car is recently new to me...... When the car arrived there was no engine light on...... now there is!

I'm hoping someone might be able to shed some light on the issue..... either from unfortunate experience or maybe if its a common thing, explain a fix ...

Gearbox was replaced in 2017. 13k ago!

I will explain exactly what happens and when the problem accurs....

When you go in to REVERSE... the car goes in to limp home mode (Solid RED lights on the dashboard gearbox icons) it does this precisely when the gearbox fully engages in to reverse..... clunk!

Dahboard then states ''SERVICE''.

All gears work including reverse, still goes backwards.

All forward gears change smoothly with no issues including the paddle shift tiggers on the steering wheel.

If I do use reverse I just turn the car off and back on, quickly cycling throught the gears to ''DRIVE'' seems to avoid any issues! The car then drives perfectly.

From what I have researched it sounds to me like the F125 switch my be at fault? Can you drive the car safely with a faulty switch or will it cause any long term damage?.... I could probably put up with it for a while. Will it get progressively worse as time goes on?

Any Advice appreciated.

Thanks Phill

[srichards]

I'd go F125 as well. That's what mine did. Also get the gearbox serviced at the same time with new oil and filters and new switch. Then see what it's like.

Mine did the lights of doom again this year and it needed a service and there was also a small leak. That affects the pressure I assume so it will make it unhappy too.

Don't drive it like that. You just increase the chance it will fail expensively and at an inopportune moment.

[Shoppinit]

Yeah. F125. When the gearbox faults out you only get 4th gear and reverse.

[Fil3807]

I'd go F125 as well. That's what mine did. Also get the gearbox serviced at the same time with new oil and filters and new switch. Then see what it's like.

Mine did the lights of doom again this year and it needed a service and there was also a small leak. That affects the pressure I assume so it will make it unhappy too.

Don't drive it like that. You just increase the chance it will fail expensively and at an inopportune moment.

I'll have to look in to the F125 switch at some point, the area I live has serious lack of RS6 support (garages that would know what to do)

I have no choice but to drive it.... its my only method of transport (I'm disabled and cant walk anywhere)

The car has only been with me a few weeks so trying to resolve issues gradually.

[Shoppinit]

Sounds like they sold it to you knowing there was an issue. Was it a private sale?

The good news is that the F125 can be changed with the box in situ, evening it is a pig of a job.

Whereabouts are you?

[steve2003rs6]

Ditto on your other thread.
Whereabouts are you ?
Someone maybe in a position to help you out.

I intend to change my f125 switch in April when I have the annual service done at unit 20 near Chester.
The switch is fine at the moment but I believe it is the original switch. So intend to have it changed before it gives me any problems.

My advice to a new owner would be don’t let any Tom dick or harry work on your car.
It will be very expensive in the long run fixing what they have done badly.
These cars really do need a mechanic who knows what they are doing.
When I first bought my car in 2012 I used the local Audi main dealers Not happy with them.
So I used other local “Audi techs” again I wasn’t happy.
This site recommended unit 20 to me and I am very happy with everything they have done.
Haven’t used anyone else for years.