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stin1974, Transmission Tech
Category: Chevy
Satisfied Customers: 765
Experience:  Chevy Transmission Tech
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Have a P0420 code. what is the fix?

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Have a P0420 code. what is the fix?
Just to be sure, is the 0420 the first code on the list?
Customer: replied 5 years ago.
P0410 is the first code on the list!
So it's those three total?
Customer: replied 5 years ago.

That is all!


If the p0410 is the first code, that is for the Secondary air injection system. A lot of times the fuse for this blows and kicks the light on. Do you have a test light to check the fuses?
Customer: replied 5 years ago.

I do have a test light! Which fuse would that be!

The P0410 code refers to the emissions system. The air pump forces air to the exhaust to lower the emissions. It takes in outside air and pumps it through two one-way check valves into each bank of the exhaust.Most of the time that this code is set, the one-way check valves have worn out or failed and allow water (which occurs naturally in the exhaust) back into the pump. In any cold climate, especially in climates with higher humidity, this water may be more excessive. The water partially fills the AIR pump, it can then freeze. When the PCM commands the pump on, if the pump is frozen it cannot turn, thus overloading the circuit and "popping" the fuse.Note: There is a technical service bulletin (TSB) regarding this code for a number of GM models. The TSB calls for the replacement of the AIR pump and the installation of a new secondary injection hose. The TSB can be found on the ACDelco web site.Additionally, if you simply replace the AIR pump the problem may return again (and again). If you replace the pump, also clean out the hoses and replace the one-way check valve. If this is on a GM model that the TSB applies to, follow those instructions in the web site above. In a few cases, people have put a small hole in the rubber cover on the pump which allows any water to drain out.Also, please note that this may be covered under the emissions warranty on the vehicle. If your vehicle is out of bumper-to-bumper warranty, check if the emissions warranty is still valid!Replace the AIR pump AND one-way check valveTest and clean the AIR pump AND test and replace the one-way air check valveReplace the AIR pump inlet hoseReplace the AIR pump fuse (found under the hood)The should pretty much explain what's most likely goIng on.
This is something a garage will most likely have to take care of and they can do the tsb info and possible warranty stuff. Jut let them know you are aware of what the problem is.
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Customer: replied 5 years ago.
In doing some follow up checking, I found that the main check valve coming from the air pump is broken at the bottom. Could this cause the problem codes to show! Part # XXXXX XXXXX