my 99 civic is showing signs of a transmission issue. i have 220k miles on my car, about 70k of those are on my rebuilt transmission (which was needed at 150k). my car is still driveable and actually rides fine. Yesterday, driving 30 miles into boston, my check engine light came on halfway into the city, i promptly stopped at a jiffy lube to use their computer. p0704 (tranny) and o2 sensor were the two results. The only noticable sign of trouble is the fact that at 65 mph in cruise control, my car is at 3k rpm (which is 500 over the normal needle resting point), and extremely light jerks about every 5 seconds at idling (in drive). I'm wondering if the o2 sensor is the cause of the rpm and jerking issue and the tranny code is due to very dirty fluid..from oct 09 to sept. 10 sat off the road with its transmission fluid of 40,000 driving miles without flush, sitting, i'm hoping this is the issue. Currently taking the train to avoid furthering issue and repair cost.

 

I would try flushing the trans ,mine had a slight jerk when changing gears and after a flush it's fine.

 

The fluid needs to be drained out of drain plug to try to wash garbage out of filter. Let it set and drain for an hour or so if you can. If the vehicle is warmed up before you start helps also. I don't recommend a flush because all the oil taken from your transmission is filtered before it goes to the flusher so all the debris gets left in the transmission.