well, probably because simple me makes it complicated.
VW is still living in the 80's by putting these stupid air injection pumps on their cars. 10 pounds and hundreds of dollars destined to fail. Like it did on the Passat. Engine light on, Pump was full of water, which means it seized the pump and the Kombi valve was also toast. New pump, but I can save money by just CLEANING the valve. With a solvent that ruins the valve. So 2 weeks later the light's back on and I'm back under the hood changing the valve. Another 2 weeks, light's on. Theses relays go bad sometimes, pop a new one in. It's right near the fuse, so a quick check, that looks fine. Another week, another light. A couple days of checking every hose, wire, vacuum line, solenoid, did the new relay die? Hey, look at that - an actual ohmmeter says the fuse IS bad. *&&*%^%&**!
It's all good now. No - wait - the dash says "check brake pads". What's that scraping sound?
All this just so I can sell this thing when the kid's new car comes in!