Will battery failure or low voltage affect fault codes VW

[rolyberkin]

I have a 2008 VW Passat Tdi which has been no issues to me during the last six years, of late I have had a few what i believe erroneous fault codes, parking brake issue (The known parking brake issue has already been dealt with) and more recently a DSG fault code. I say they may be erroneous as on Thursday last week the indicator came up service now and today it is showing 60 days or 1800 miles which is about right.

A few weeks back it wouldn't start and I recharged the battery, today I couldn't start it and had the battery out which is not the correct size (undersized) for the car and I think is failing as it is showing quite low volts. I have additional AV equipment (video screens) for the car and it does a load of short journeys.

Anyway after opinions, could fault codes be caused by a poor or undercharged battery?

 

[Wilko]

Hi - yes I've seen this before. My process is : load test battery and or replace it with the biggest one that will fit. Once a new battery is in place clear the stored fault codes and see if any return.
I think the cause is that starter cranking causes battery voltage to drop enough to cause weird and wonderful "faults" to be detected by engine mgt system.

 

[rolyberkin]

Thanks, have changed the battery from my Golf into it today which is when I realized someone at some point in its life has put in a smaller battery (used to be a lease car so could have happened at any point) will see how it goes over the next few days and also run a parasitic draw test on it tomorrow.