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

asked by on December 25, 2016

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.

Air Pump Check Valve Replacement $104.38 - $535.13 Get a Quote

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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

Car slowly lost power and wouldn't accelerate. Then when I pulled over and it started smoking and now it won't start.

Check the back of the engine by the firewall for any burned wires. It is possible that the harness to the engine has fallen down onto the exhaust manifold and is burning through. The wires may have shorted to the...

My traction control is off and half of the engine doesn't work, I hooked up a computer to it and the P0800 code is on

Hello, thanks for writing in. P0800 is the trouble code for an issue with the vehicle's Transfer Case Control system. When the transfer case control module, a computer that is separate from the engine computer, detects an issue with the...

P0491 and P0492 Is the codes I'm getting on 2001 BMW 325i

Hi there - the P0491 and P0492 codes reflect a problem with the secondary air injection pump mechanism - not enough air flow is detected. This problem could be the pump itself (check fuses and relay), the check valve, or...

Doesn't rev past 4k revs

You may have a mass airflow sensor that is contaminated or not working correctly. The sensor can get contaminated by dirt, debris, and oil from aftermarket oil-type air filers. You can try and clean the sensor and use a standard...

jumps and surges at 45 and 60 mph

The most likely cause for this is that the transmission torque converter overdrive lock up clutch inside the converter is chattering when it is engaging after about 45 mph. The problem may be with the solenoid that operates it or...

Overheating after brake modulator replacement

Hello there, there are a few things may have happened to cause your 2000 Cadillac Catera to overheat. The most common would be a radiator cap failure, air in the cooling system, or the wrong type of coolant. A qualified...

Antitheft feature shut down

There are a few things you might attempt to see if the system recognizes the keys again and resets itself. You can try to lock and unlock the drivers door using the key. This will sometimes reset the system by...

I have a 2001 Lincoln LS and the spark plug on the number 8 cylinder is leaking getting oil on the spark plug what do you think th

Sometimes there can be oil on the spark plug threads but the plug itself is not fouled. If the firing end of the plug is OK (not fouled, and not covered with liquid oil and so forth), the cause of...

ford focus air bag light on all the time

You cannot reset the airbag light unless a scanner that can access the airbag system is used to check and retrieve codes. Once codes are received then a diagnosis can be done. It is recommended that only qualified mechanics test...

Related articles

Symptoms of a Bad or Failing Exhaust Gas Recirculation (EGR) Tube
Common signs include rough idle, rattling noises from the engine, and the Check Engine Light coming on.
How to Buy a Classic Cadillac
Cadillacs are the ultimate in luxurious domestic vehicles and have been for more than century. Classic Cadillacs have been under the General Motors umbrella since 1909 and consistently rank at the top of a list of premier automobiles. Classic...
Symptoms of a Bad or Failing Throttle Body Temp Sensor
Common signs include poor engine performance, stalling, and broken electrical connections.