Check the Junk in Your Trunk
The first thing you should check is the compressor and its housing located under your spare tire in the trunk. If the spare tire well has any sitting water, you might have a much larger electrical issue at hand. The sunroof drains are known to clog on the E60 and E61 BMWs. This needs to be cleaned out periodically or they will drain into the trunk and ruin your rear air leveling compressor pump, relays, and suspension control module.
What’s Under That Spare Tire?
The dome housing under the spare tire holds your suspension compressor pump, relays, automatic height control module, and other electronics. Check the air line running from your compressor pump and take notice of the type of tubing. Many newer models 5 Series came with a braided inlet air line running to the compressor, because the compressor is known to vibrate while pumping air which in turn rubs the air line until it cracks or punctures. This causes the compressor to take in unfiltered air/dirt and clogging up the valves until it stops working completely. If you have the plastic style intake air hose, it is recommended you replace it with a braided line, and many DIY mechanics suggest using fuel line as the replacement.
When your BMW sags in the rear, you most commonly have a leak in your air suspension somewhere. If only one side is lower, you probably have a leak in the air spring on that side, but if both sides are low, you may have a leak in the air line running to the springs. A solution of soapy water solution sprayed onto the bellows and the tubing will tell you where the leak is located by looking for the quick bubbling. The rear air springs are simple to replace, just by lifting them from the lower mounting point and turning them a quarter of a turn, and they should pop right out of the top mount.
Suncore Industries stocks the components you need to replace your E60 and E61 rear air suspension, including the relay and elusive solenoid valve block. We are proud to offer quality parts at much lower prices than the dealer, with free technical support always included. Call or email, and let us show you how we can help.