Echo Check Engine Light

[nfrailway]

My 2002 Echo is showig a p440 code. The car runs great but the check engine light keeps returning every 4-5 days after clearing the computer. I can't find anything wrong under the hood, disconnected hoses etc.. I replaced the Denso plugs myself with NGK G-Power platinums. I don't suppose this could be the problem.

[lemonjenny]

I had this same problem, and it was a Vacuum Hose that had slipped off.

I've also heard it can be a loose gas cap.