i have a 99 Mazda 626 cuts off at stop lights was told it could be a few problems. Check engine light on. Runs fine until sitting in drive at stop light.
1. Needs tune up (bad wires or plugs)
2.Air fuel mix (o2 censor etc)
3. Vaccum leak
i live in the cincinnati Ohio area any leads need fixed asap or good diagnosis so i can buy parts and fix myself if possible thanks everbody for the help

 

Do you have a 4 cyl or a V-6. What codes do you have. Please Post some trouble codes. Need more info.

 

autozone code says P0421 i think its a 4 cyl i looked into it somebody else told me it was an IAC Valve not sure this is my first foreign car so no good on figuring it out

 

You probably do need a tuneup and it's not a bad idea to check for vacuum leaks in the process. Your trouble code indicates that your catalytic converter has already been damaged by driving the car while in need of a tuneup.

Putting off a tuneup used to mean that you would be driving for a while at less than maximum efficiency. Putting off a tuneup in cars with modern emissions systems means that you are doing some very expensive damage to your vehicle.

 

You don't say how many miles you have on the car. When you say "needs a tune up", based on what ? How long have you been running with the CEL on ? If you reset it (by lifting the battery connection and leaving a door open for a few minutes), how soon before CEL reappears ?
code P0421 is warm up cat. efficiency. It means the rearmost O2 sensor has detected incomplete combustion. This could be the cat. but also could be the O2 sensor itself, or fouled up plug(s) which fire OK, but fire across the carbon deposit and don't "flash" a clean spark for the cylinder burn.
Other remote possibilities are that the MAF or upstream O2 sensor are defective, signaling more inlet air than is true, hence calling for more fuel than there is air to burn it with. Finally, injectors or fuel pressures can be the culprit.
Get your tune up done first, preferably from an authorized dealer. Run the car for a few days afterwards, then re-assess the situation. If cats. or O2 sensors have been sooted up but are otherwise undamaged, a hot run with correct fuel/ air mixture can quite often restore their health. The cat. is expensive, so change it as a last resort.
Note: Unless the car was neglected, or wrong grade fuel used, cats. and O2 sensors should be good for 100,000 miles or so.
Make sure you have a good mechanic, and only use OE parts for O2 sensors and cats.

 

Thanks board will get the tune up asap ever heard of the IAc valve being dirty will et u know what happens car has 85,000 miles

 

Here are some links from another forum that might be of interest to you. They apply to similar problems with different model years:

http://autorepair.about.com/library/faqs/bl964h.htm

http://autorepair.about.com/library/a/1g/bl983g.htm