Q: Problem with secondary air injection and the idle is hunting.

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Getting engine code p0410. I start the car..it runs smooth while the air pump is on..when the pump switches off it will go to a hunting idle. As it gets warmer it will level out for a while then go back to hunting back and forth. Only stays idling smooth when the engine is fully warmed up. I have confirmed there is air flow going to the diverter valve. The check valve seems to be functioning properly. Ive replaced all damaged vacuum lines and checked the rest for vacuum and all seems good. Im afraid the diverter valve may be bad but ive not yet checked it. I would like to get a second opinion before i go to a shop...could it be a simple bad relay or something else?

My car has 222000 miles.
My car has an automatic transmission.

Hi there. When the air pump is working and the engine is running fine and then when the air pump is turned off and the engine idle starts to hunt, then there may be water in the air pump or the vent solenoid could have failed on the air pump. Check the air pump and make sure that its functioning correctly. If the pump is working like it should, then check the hoses on the air pump for any dampness. If they are damp, then the pump may have water in it and the pump would need replaced. If the pump is dry and the lines are dry, then the vent solenoid could have an issue and not purging the pump and the solenoid would need replaced. If you need further assistance with the air pump not working](https://www.yourmechanic.com/services/air-pump-check-valve-replacement) properly, then seek out a professional, such as one from Your Mechanic, to help you.

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