Cadillac Repair: Code 49/ Auto leveling system, cadillac deville, faulty component

Question
I have a 1990 cadillac deville with a 4.5L engine.  The Auto leveling system in the rear of the car doesn't seem to be working (occasionally the tires rub against the wheel well if I hit a bump).  The compressor does work, and it comes on after I turn the car off.  How can I tell if the problem is a broken air line or a malfunctioning height sensor?  Also the trouble code E49 came up on the diagnostics, and I had the air diverter valve replaced a couple of months ago. Where should I start to look for this problem?

Answer
To check for a broken air line trace the air line from the compressor back to the hoses on the shocks/struts.

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