Does anyone know if battery depletion over several months ( as in down to maybe 1.5 V ) will cause fault codes to be logged in the e.c.u. ?

 

And what about battery connection and dis-connection ? Does that cause the same thing ?

 

This is all without the engine being started.

 

Thanks.

 

if you had to open a door and/or the bonnet to disconnect the battery then 100% yes.

 

Disconnecting and reconnecting a battery with a reasonable state of charge will not cause problems other than dashboard lights which will go out after driving 25m and the window motors having to relearn their power and position settings.

1.5v is pretty flat, did you manage to recover the battery and if so how, and how is it performing?

To add to JRs comments, I changed the battery on our Yeti last month to a new Varta one.

 

3 or 4 warning lights (ABS, ASR,ESP?) and the steering one which went off once I turned the steering from lock to lock and moved the car back and forward.

I thought I may have had to replace the battery on our Yeti this winter as it's now 9 years old but it's still performing fine.
Just an aside Carista now has battery registration and a lot more things for the Yeti as well as running fuel pump prime.

Edited 29 January, 20242 yr by Urrell

On 29/01/2024 at 19:22, J.R. said:

if you had to open a door and/or the bonnet to disconnect the battery then 100% yes.

 

Disconnecting and reconnecting a battery with a reasonable state of charge will not cause problems other than dashboard lights which will go out after driving 25m and the window motors having to relearn their power and position settings.

1.5v is pretty flat, did you manage to recover the battery and if so how, and how is it performing?

 

I did not try to resurrect the battery once I saw 1.5 V on the multimeter, based on past experience with highly discharged batteries. If the discharge had been quick ( say like lights left on overnight - maybe these "modern" cars won't let you do that ?  ), I might have tried but I am certain this was a slow discharge over many weeks caused by operator error ( me ). I had other things going on and it just escaped my mind, as also the car wasn't running at this stage so that made it easier to forget to keep the battery charged. A quite expensive lesson for me.

 

( Yes I got those dash lights too after a battery change, but as you guys said, they all disappeared quickly. )

 

The reason I asked this question about fault codes in the first place was I tried VCDS for the very first time a few days ago and got a ton of fault codes showing on the Auto Scan results. That made me think that maybe the very low battery voltage may have caused mayhem with the various systems (naive as it seems now). But today as I gained more familiarity with VCDS, I looked more closely at the information and saw that pretty much all of the codes had dates from long ago, like 2016. 

 

Thanks for the responses.