hi. I have a 95 mazda 626 LXV6 with 182000 miles on it. Car runs like a champ but has a minor problem. Intermittantly at speeds of above 65, the check engine lamp comes on for about a mile or so and then goes out. I've noticed that if I let the car come down to 60 and then feather the gas, I can get the light off until the next time. I don't notice any changes in engine performance to correlate with the check engine lamp. I just replaced the bank 1 upstream O2 sensor and still have the same problem. Was planning a trip to South Carolina but couldn't play cat and mouse with the check engine light for 1000 miles each direction so I trashed that idea. Any suggestions?

 

You need to have the car scanned for codes to know what its trying to tell you.

A guess would be the EGR valve from what you are describing. EGR problems usuallly manifest themselves at highway speeds and are not noticeable. I would venture an EGR low flow code.
The EGR system will have carbon build up in the passages that is normal on higher mileage engines.