Hi chaps. 
My car alarm is starting to go off in the middle of the night since last Sunday. I have read a few posts which points to a failing battery. I had it tested today and although it read as good it is barely above the line. I don’t want to go to Halfords or the like for a fitting and would prefer to buy a good quality battery and fit myself. The issue I have is the coding of the new battery. Could any of you recommend a cheapish OBD reader which has this functionality?

 

Thanks in advance

Is it not the 'Failing battery in the Alarm Siren' rather than the cars battery? 

 

What age is the car?

Thank you, it is a 2017. I’m not sure if/when the main battery was ever changed. I didn’t consider a failing battery in the actual alarm itself and am guessing this is a big world of hurt!

Maybe not so cheap, but will do battery coding and electric handbrake service release/ reset as well as a load of fault code reading.  Might pay for itself once used a couple of times?    Mine has!

https://m.gendan.co.uk/product_FXNT530VAG.html

 

Edited 4 December, 20241 yr by Shuggyboatsuperb

Hi, you could use CarScanner to code the battery !!! see the code Vendor in RossTech forum if you have not BEM code

Thanks guys, do you know if it’s a big issue to replace the alarm module if that’s what is the problem?

A good OBD scanner/reader could also point an eventual failure in the alarm system.

Why don't you look for some Briskodian in your area that has/offers assistance with a diagnostic system such as VCDS?

I'm afraid it is very unlikely to diagnose a failed or failing lithium battery on the alarm module PCB, my VCDS never showed any fault codes until the acid corroded the tracks and the module stopped communicating with the Canbus Gateway, the siren even worked using the Output Tests.

 

To the OP there is nothing to indicate that your vehicle needs a new main battery so you can stop worrying about the coding of a new one.

15 hours ago, MartinBolge said:

Thanks guys, do you know if it’s a big issue to replace the alarm module if that’s what is the problem?

 

The car alarm and it's battery is a combined unit, and is located inside the b-pillar.

U can replace the whole unit with a new one.

They usually last 6 yrs or so..... depending.

 

 

 

Thanks J.R. for clearing that up, now we know 🙂