Whilst driving back from the shops today, the battery light on my Mk5 1.9 CDTi came on and I also noticed that it began idling at around 1100rpm instead of just under 1000rpm. I had to make another stop along the way and so when I restarted the engine, it seemed ok but then after a minute or so, the battery light came back on and again it started idling above 1100rpm. I'm getting a fault code 621. Is it just that my battery needs replacing? The battery had died a couple of weeks back due to some faulty wiring on the amp courtesy of halfrauds but i got that fixed and it's been fine since. Your advice would be appreciated.
Thanks for the assistance.