I've been trying to fix my P0410 code for the last month using the information contained in the sticky thread. Here's what I've done so far:

1. Cleaned and checked the valve. Seems to work (allows air to pass in 1 direction only)

2. Cleaned the ground wire for the air pump

3. Cleaned the contacts on the relay. There was a little burning but they didn't appear pitted.

4. When I start the vehicle there is power to the harness as indicated by a test light. I should probably check with a meter to get exact voltage.

5. When I apply direct battery voltage to the air pump I get nothing. Maybe a couple grunts, and then silence.

So I purchased a new Bosch air pump and installed it. Cleared the codes. I thought that would fix it but the code came back within 15 minutes of driving the car.

So I've run out of ideas here. What else to check?

Thanks

Curt