00 Subaru Outback hiccup at cruise


#1

My 2000 Outback 2.5l hiccups at cruise. Usually it is worst at highway speeds, but can happen at any speed if cruising at a constant speed. It will accelerate fine at any speed and idles fine as well. 95% of the time the CEL does not come on, but the other 5% of the time the light comes on as well as the AT Oil Temp light(auto trans) and it shifts hard and stays in gear until I restart the car. It has pulled a P0122 code which is the Throttle position sensor circuit low input a few times thus I have replaced the TPS twice with absolutely no change? Any ideas? I thought something with the ECU trying to lean out the mixture at cruise, but leaning to much? Please Please help this has stumped everyone so far! Thanks! Sean


#2

Is the engine misfiring or is it something in the transmission? A misfire will turn on the CEL and set a code, but I don’t know why it would also turn on the AT oil temp light.

The transmission fluid is clean and at the correct level, isn’t it?


#3

The TPS code may be due to a wire connection problem rather than the sensor itself being bad. I would check all the connections between the sensor and the ECU for that circuit to see if there is any problem.