Hi everyone, my name is Dave and I own a 2007 civic ex m/t with a cold air intake. This is my everyday driver and when the intake was first installed I was throwing the code for running rich but since then the car hasnt had anything. However, a few weeks ago my cel came on and went off about a day later. Then four days ago it came back on, I figured it was the same code. Today, I checked for the hell of it and it is throwing two new codes. The codes are P0420 for the catalyst efficiency below threshhold and P0103 for the MAF circuit having a high input. What do you guys think this may be? Thank you.

 

welcome to the forum. Seems from changing your cold intake, your codes seem to appear, perhaps there are some lines or sensors that have not been hooked up properly or you may have bypassed that is causing the codes to come up. Also if you have a warranty, you might want to check with your Honda service dealer if it is ok to install the cold intake, you can void your warranty when anything is added to your new civic.