I recently had a code come on for a cylinder 4 misfire. The ignition wires were pretty shot and the plugs for the whole engine were due for a change. I replaced all the plugs and wires. When I was reassembling the airbox, I noticed that I had lost the plastic 90 degree elbow that comes out of the lower airbox that connects to another plastic hose. I tried starting the car without the elbow and the car runs ,uch better but now I have the CEL light on again. Does the elbow I lost connect to the secondary air system? Could this cause the CEL to come on? Anywhere I can get a new elbow for cheap? Any advice would be greatly appreciated Thanks!

 

That is a feed hose for the SAP, but without the elbow, it won't throw a code, it'll just feed unfiltered air to the pump. You can replace the elbow or just get a small cone-style breather filter for it at Autozone. They can also scan your car and give you a printout of the fault codes triggering the CEL. Get that and post the code(s) if you want assistance in deciphering their significance.

 

So I went to autozone and it is showing the same code P0304. The car bucked and was definitely misfiring before but it runs super smooth now with no misfire. The autozone guy said if i drive it a while, the code will go away on it's own. Is that correct? I tried disconnecting the battery but maybe it takes more than that to clear the code. Any ideas? I would really like to drive my car again since I have been borrowing my girlfriends car to get to work. Thanks

 

Codes will never go away unless they're cleared properly with VAG-Com or an OBDII scanner. The check engine light triggered by some codes will go away if the condition that caused the code corrects itself, like fuel trim or O2 sensor readings for example. As long as the engine isn't misfiring anymore there's no reason you can't drive the car.

 

It's a pointless part. Ignore it.

 

Do they have emissions inspection in AZ? If not, this ^.