The car is a '98 V90. First thing I did was search the archives here on PO410. Learned a bit of what to look for.

We've had this fault appear a couple times before. First time, we had the check valve replaced -- guess that's what you call it. It's the one bolted to the head that has the big hose connected to it from the air pump and a smaller plastic hose that runs over the engine and connects to a vacuum source on the drivers side fender well. Second time, the hose and rubber elbows were replaced.

Looking under the hood after starting the engine, I held the airpump in my hand and both hear and feel it operate for 20 seconds or so. This is normal from what I've been told. I noticed that, of the three rubber cushions that hold it in place, two have deteriorated, and it is now just hanging in its bracket. I called my Volvo parts guy and he says they're available by themselves, so I'll be replacing them.

So, I'm wondering, given that the air pump works, the valve has recently been replaced, and the vacuum lines are good, what's left? Is it possible that the error code was sent because the pump was not sitting perfectly horizontally?

Best,

Michael