Can anyone give me some direction on a code P0440????Evap Emmision Malfunction.......... 1999 Blazer

that means there is a leak in the evaporative emissions system. the only way to find it is to smoke the system and pinpoint the leak. it could also mean the the fuel cap may have been loose.

99 pecent of the time is just you forgot to tighten you gas cap after you filled it.
chris

I've been getting this code since I bought out blazer. (used) Every EVAP test done, 4 of them now, has shown no leaks. According to the code list, there are 2 different codes for leaks. One for small leaks and one for large leaks. I've learned to live with it. Lately the wife has been complaining about poor mileage and SES light came on again. Showed P0440 code AGAIN. Replaced the gas cap twice.

My question is will this code set the ECM into a preset run like it does for some other codes which would result in the mileage drop? I cleared the codes again and will try to get her to check her mileage. She never calculates it she just goes by the total miles per tank. Usually she gets 300+ miles from tank, last tank was down to 195. No noticable change in the way the blazer runs, but I think its underpowered, but I'm used to driving my truck.

Any thoughts on this?

Thanks,
Chris


Edit: 98 Blazer 4x4 4.3 Auto