i get a weird message that says reduced guard when i turn my car on and the check engine light came on when this message came up but the message is only up when i turn the car on. does anyone know what reduced guard means?

 

I'm guessing it has something to do with the alarm system. Do you have a perimeter sensor in your car (there will be a switch under the climate control). It's possible the switch was pressed, causing the perimeter sensor to become disabled (or reduced guard) or something is wrong with the security system.

 

I believe it may also have something to do with the interior alarm sensor not being enabled?

 

I know it is a 2 year old post, but after the grandkids left, my 2001 S80 T6 began displaying "Reduced guard -- see manual". Nowhere, absolutely nowhere in the manual is the term "reduced guard" addressed. Glad the OP had the problem. Now I know where it came from.....kids hitting buttons.