Brake fluid level sensor

[alg]

I have had the old problem of false (!) alarms after a period of non use on the previous S2 & the RS2. The only time it was true was due to a hydraullic fluid leak from the pipe out of the hydraullic fluid container.
Now the car has had new front discs & brake fluid service. The alarm goes off over every bump!!
All the levels are OK. How does the brake fluid sensor work ?? Does it detect pressure in the system or just low levels or high levels ??

[Mikes2]

There's 3 sensors which can trigger this.

Hydraulic fluid level sensor
brake fluid level sensor
hydraulic pressure sensor

I had an issue with the brake fluid level sensor on my 90 quattro 20v. Disconnecting it got rid of the warning but replacing the plastic slider at the base of the reservoir made no difference.

Ended up replacing the reservoir with a 2nd hand one as I couldn't get to the float.

[alg]

There's 3 sensors which can trigger this.

Hydraulic fluid level sensor
brake fluid level sensor
hydraulic pressure sensor

I had an issue with the brake fluid level sensor on my 90 quattro 20v. Disconnecting it got rid of the warning but replacing the plastic slider at the base of the reservoir made no difference.

Ended up replacing the reservoir with a 2nd hand one as I couldn't get to the float.

How easy is it to replace ? Why could you not get to the float ?
Thanks Mike

[Mikes2]

The reservoir just lifts up from the master cylinder. You need to clamp the clutch feed hose and have some rags around to catch the fluid.

Couldn't get to the float as my fingers couldn't reach into the reservoir. Even after removing the gauze protector, there's not much access.

I take it you've verified the brake fluid level sensor is the culprit

[alg]

Well in as much as the bomb passes its test & all fluid levels are correct. In addition it seems to come on going over a bump or turning at low speed. Suggests a fluid level shift is causing alarm rather than pressure.

I will verify by removing the sensor connector (checked it a few times re good contact)

[Fat Audi 80]

Al, I have had that on the PS Fluid reservoir before, it seems the actual connection to the lid of the bottle was dodgy. Undid the lid and did it up again and it was okay.

Have you checked this too?

Kind regards,

Steve.

(I guess it probably is the Brake Reservoir, as the has been recently worked on, but worth checking both...)

[Greg_S]

Also check the PAS float isnt getting stuck, you should see the nipple poking out of the top of the reservoir

[alg]

Well seemed to sorted this by 'thumping' the brake fluid reservoir..........no alarms since. Me thinks a sticky is in order. If you get the old red (!) & the bomb passes & fluid levels are OK, just thump the reservoirs !!!!!!!!!!!!!!!

[BrianSmith_S2]

Well seemed to sorted this by 'thumping' the brake fluid reservoir..........no alarms since. Me thinks a sticky is in order. If you get the old red (!) & the bomb passes & fluid levels are OK, just thump the reservoirs !!!!!!!!!!!!!!!

Or unscrew the cap/float assembly and give the contacts and switch a good clean (i used carb cleaner) ensuring its dry before its refitted to the reservoir.

I recently got this alarm when starting the car first thing in the morning after i had bled the system and overfilled the reservoir. i think the fluid had got to the cap and messed it up inside.

After the clean, and removal of some fluid, its been ok since

[alg]

Or unscrew the cap/float assembly and give the contacts and switch a good clean (i used carb cleaner) ensuring its dry before its refitted to the reservoir.

I recently got this alarm when starting the car first thing in the morning after i had bled the system and overfilled the reservoir. i think the fluid had got to the cap and messed it up inside.

After the clean, and removal of some fluid, its been ok since

Brain are you not referring to the Hydraulic fluid reservoir ?

[BrianSmith_S2]

Brain are you not referring to the Hydraulic fluid reservoir ?

Yep...thats the one that was causing the (!) to come on. as mentioned a few things like low pressure, low brake fluid and low PAS fluid level can set this off afaik