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Q: Check Engine Light????? on 2004 Mazda Mazda6

Last night I had the check engine light go on and AT flash on the dashboard, this is the first time the check engine light has ever gone on. I have 72000 mile on the car, and have had no problem at all before this.
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the A/T light being on means that there is a transmission problem detected and "trouble codes" stored by the computer. An A/T light coming on probably turns on the check engine light too so there may not be an engine problem, it's just that the light comes on to get your attention. I believe that some of these cars had a computer internal electronic defect which may be covered at least in part by Mazda. Or you may have a simpler problem, that's a defective transmission "turbine speed sensor" which is easy to diagnose and repair since it's attached to the outside of the transmission meaning that you don't have to rebuild the whole thing to fix it. Only a Mazda dealer can warrantee a computer problem, or you could also go to a good transmission repair shop, they would scan for codes and at least tell you what's wrong, recognizing a common problem. Either way, you will need a mechanic with a scanner to read the codes, diagnose your car, and clear the codes after it's repaired.
I have had the same thing happen twice on my 2003 Mazda 6 and have had it on the computer, shows not error codes and to a transmission specialist whom scanned for codes also, they could not find out what the issue is. "AT" turned off right away and eventually the check engine light goes off. ?? My Mazda feels like it is slipping or lagging. I also thought it was the transmission.
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