A really weird issue when car is cold!


Registered User
Mar 9, 2016
Reaction score
Hey guys,

I've just realised that there's a really weird issue that I am encountering with my car, its only recently I've realised this since I've retrofitted a rear view camera to it.

Basically issue being that when I start the car and while its still cold, the rear view camera doesnt work and trying to inspect this I found out that the reversing lights dont come on either when engaging reverse gear, however this is only during the time the car is cold so after a little while and the temp increase, both the rear view camera and the reversing lights start working without any issues!

There dont seem to be any errors while they're working but when its cold I do get an error regarding the camera module not being able to communicate with the gateway, this error disappears once the camera and lights start working.

Completely baffled with this, anyone else had any similar issues?!
As above it could be that the car is controlling the load on the battery and not everything is available. If the battery voltage drops too low things start to be switched off. How old is the car ? .
Hmm, thats interesting, unfortunately I dont have a multimeter to measure the voltage and since I have the 3G+ MMI retrofitted I cant enable the battery monitor option.

Any other ideas to get that measured, what should it be?...any other indications of a weakening battery?
The battery monitor option only gives you a bar, it doesn't give exact voltage. You should buy a multimeter off eBay or something they are only a few quid.

I'd stick mine on there for you if you are anywhere near me. I think some garages do a free battery check for you though, might be worth popping in to Kwik fit and saying you think your battery might be duff. You need to measure it when engine off otherwise you'll be measuring alternator output and not the battery voltage
A good rule of thumb when checking a battery is
11.8 volt is flat
12.3 volt is 50%
12.8 volt is 100%
When Charging should be 13 upwards
Not sure what the emergency cut off voltage is but mine done it last winter with only one bar on the battery display , once fully charged my display is nearly always 100% and I've never had the cut off emergency message again
Is it 13+ on Audis?
I've always expecting 14.6v with the engine running.
Should have said 13volts upwards some cars have smart charging systems of over 15 volts
That's a really strange problem. With the engine running the reversing lights should work whatever hot or cold. If you disconnect the power connector to the reversing camera module does the reversing light work as normal, for example ignition on, but engine off?

Similar threads