SIA date wrong for brake fluid timer

[Shonky]

So I flushed my fluid today. No real issue there but when I reset the timer it appears to have an incorrect current date (this happened previous times I did it too)

It wasn't flagging a change was required ie no clock. Entering the menu it showed as 4.25. My records indicate I did it last in July 2023 so that lines up with what happened when I reset it.

When I reset it, it changed to 11.26 ie it seems to think it's November 2024 right now apparently - about 3 months "slow"

Car is all stock except for a home-built BlueBus. No modules eg the IKE have ever been replaced.
Date and time are correct on the Nav display.
Setting the time from either the dash or the on board nav correctly updates the other immediately.

So it seems like the SIA is keeping its own date internally.

I've not found anyone else having this problem or any references to correcting this SIA date. I know it will still only flag in 2 years from now even though the absolute date is wrong. But it does mean you can't just use it to check the due date and it hurts my OCD

Any ideas?

[bmwfnatic]

I remember it to be a day counter, by default it counts down 716 days if I remember correctly.

[Shonky]

I remember it to be a day counter, by default it counts down 716 days if I remember correctly.

Yep and you can change that I think with the PA Soft tool. Should be 730 for 2 years so wierd they chose 716. 2 weeks short I guess as a warning?

It still reports MM.YY when you do the reset though so it's more than just a day count down.

Perhaps it is really dumb and just counting calendar days it's on so if left unpowered for long periods it starts to lose time? In my time (about 15 years) it's never been unpowered for any significant time.

They really should have just done it as day countdown and when resetting just let it set back to 716 or 730 rather than try and bother with a month and year.

[elrichmeister]

Wow ive owned a non-m e46 for 15 years and never knew there was brake fluid timer and we had to reset. Granted i usually service my cars with an indy and typically flush brake fluid every 2-3 years. Where do you check on brake fluid time?

EDIT:
Did some google-fu and apparently this indicator light is only on euro models or non-us?

[Shonky]

It can be disabled so perhaps it is in the US. Might also explain why there's not much info at least on English speaking forums.

Anyway, hold down odometer reset button
Switch key on to position 1 - keep holding button
Dash will display test - keep holding
Eventually it will display SIA with the mileage remaining for oil service or inspection
Release button
Short press button again and it should show a clock icon with MM.YY format of the due date. If it's disabled I'm not sure what yours will say.

Here's a demo

https://youtu.be/ItkdY0d3Koc?t=55s

[Shonky]

Had a bit of a dig through the IKE EEPROM with NCSDummy helping a lot.

I can see the MM.YY coded as BCD right next to a byte containing 25 for the year (although I think it may be year + 1). There is an apparently unused section according to the SPDaten that looks a little bit like it could be a month counter similar to how the odometer counts in the first 32 bytes.

The actual timer just counts up (not down) in days and when it hits the 716 days, the service is flagged.

For the odometer rather than storing in one place it has 16 locations that can only count up and basically it spreads writes across the locations sequentially by a shifted amount to wear level. So roll-over would be 1048575 km for a 16 bit entry but I suspect it would just stop at 999999. Neat way to do it.

Not really necessary for the month IMO (endurance is something like 1M erases per byte hence the odometer effectively dividing by 16 to easily get to 1M kms) but might be it. I'll have to read it every month or so to see what happens with those bytes.

[Warhead]

Thanks for the info in this tread.
I disconnect the battery every winter because the cars pull to much current when the temperature goes below ~1 degree Celsius (~34 Fahrenheit).
Its intermittent and it draws this strange current more and more often when the temperature drops. I think it is a bad soldering joint somewhere that disconnect when the temperature drops which in turn wakes up the car. That heats up the joint and the car goes back to sleep. Very hard to locate.
Anyway:
To days date: 2025-10-01 (did break fluid change + reset)
Next break fluid change: 2023-12-01 ???
My car thinks its 2021-12-15 (2023-12-01 minus 716 days) 😉

Conclusion:
I’m no exert but it seems that the day counter stops when there is to power.

[Shonky]

Thanks for the info in this tread.
I disconnect the battery every winter because the cars pull to much current when the temperature goes below ~1 degree Celsius (~34 Fahrenheit).
Its intermittent and it draws this strange current more and more often when the temperature drops. I think it is a bad soldering joint somewhere that disconnect when the temperature drops which in turn wakes up the car. That heats up the joint and the car goes back to sleep. Very hard to locate.
Anyway:
To days date: 2025-10-01 (did break fluid change + reset)
Next break fluid change: 2023-12-01 ???
My car thinks its 2021-12-15 (2023-12-01 minus 716 days) 😉

Conclusion:
I’m no exert but it seems that the day counter stops when there is to power.

Well yes it has to stop with no power. A clock or timer can't run without some power source. There may be something internal to keep it running for short periods but it definitely wouldn't last months.

That's kind of the issue. If you disconnect the battery, the month/year counter will stop (possibly saved with more precision than just month/year). When power is reconnected, it starts again.

When you reset the brake fluid SIA all it does is adds ~2 years to whatever the current counter is at. So the 2 year interval will remain accurate (as long is it's powered) but the listed date will gradually fall behind each time power is removed. So you can't just lookup the date. You have to rely on service records or just wait for the symbol to come on.

In my earlier post I said mine hadn't been powered down for an extended period but that's possibly not correct. It did have some time on a bodyshop which took 2 or 3 months. Quite likely battery was disconnected much of that time which would explain much/most of the error I saw.