I have a 2000 Accord that failed the emissions test because the check engine light was on. It is code P1457. The mechanic said the “evap vent valve” was bad and replaced it. BUT, the light came back on. What should I try next?”
Well, you may not like this, but I’ve seen it happen before. The vent valves do go bad, but sometimes when they do go bad, they feed electricity back to the main computer and short that evap circuit out. I’ve fixed a couple accords like that and had to replace the main computer along with the vent valve. Those computers use very small amounts of electrical power so their circuits can’t really be fused for safety. So when a short occurs on something the computer operates, it can feed back to the computer quickly and fry the circuits inside that operate that function.