I have a 2005 Suzuki Aerio with an automatic transmission. Occasionally, maybe once every month or two, the check engine light will come on while I am driving and the car will immediately stop down-shifting from 3rd gear. The car otherwise seems to run fine but I end up having to manually shift to get to wherever I am going. Then on my next trip, the transmission will shift fine but the check engine light will stay on for an additional trip or two and then go off.
I have no idea what is going on. Help! I have not had anyone look at it because by the time I get to it the light is off again and the car seems to function fine.