Every morning for the past 3 days I've woken up to my rover sitting on bumper stops. Both bags deflated. Is it coincidental that this started once the temps dropped to -10º overnight? When a bag leaks do both sides drop? When i start the truck the truck gets back to normal high within a few seconds and doesn't drop while driving

 

Cold weather shrinks the various seals in the system, so the air leaks out. It's a pretty common issue.

 

So just let it be or replace? The bags are 2 years old

 

You might want to replace them eventually, but they may always leak down in very cold weather. Mine are a year old and they were on the stops yesterday morning.
I got myself a set of coils that I'm going to install instead once it gets warmer. That's really the only way to be sure that the rear isn't going to sag.

 

Mine does the same thing when it drops below Zero. It seems worse when I have several days in a row when it never gets above 20°.

 

It can only be one of two reasons, the air suspension bags letting air out or the valves in the compressor letting by air. Eliminate the rear air suspension by raising it on the 'offroad button' and spray the suspension bags with soapy water including the entry fixing and if this proves OK it has to be in the compressor unit or the air lines to the SLS bags. Don't forget to clean or replace the air filter behind the rear drivers side light for which you'll need to remove the light fitting.

 

If it takes several hours for them to go down, you're not necessarily going to see any bubbles because the leak is so slow. Often it seems to be the o-rings in the fittings that shrink in very cold weather rather than a problem with the bags themselves.

 

Well now it won't keep air in the driver side bag, once the compressor turns off it empties in 2 minutes. It being -40 probably doesn't help. I'm stumped. It holds air after being parked for 3 days , but is on bumps when I go to the bank for 5 minutes and holds air again over night.

 

Inside a well heated garage......
......