Hello,
I'am posting this to help someone with a similiar problem I experienced with my saturn 2003 sedan. While driving on the freeway from the san francisco area to the central valley my car lost power and then died in the mountains.
This senerio happened several times. I was able to pull over and after waiting about fifteen minutes it woujld then restart and run ok for about 1/2 half an then it would do it again. I Finally called the AAA and had it towed home.Since I no longer felt comfortable driving this car because, I didn't want to get stranded on the road.
The next day I took it to the mechanic they did a diagnostic test and found codes-po-171 , po174,po463,po154,and po 134. These error codes were in my cars computer memory, but the car was running fine and the mechanic could not find anything wrong with the car since the check engine light did not come on. He said to keep driving it until it did it again and the check enging light came on. This would leave an
error code in the computers memory.
In contrast to the mechanic's advise I game my car a 100,000 service tuneup. Changed out the park plugs,
fuel filter, and had the fuel injectors cleaned out because I drive back and fourth to the san francisco bay area and didn't want to have any more problems in the mountains.
On a return trip to the san francisco bay area and on the way back home the car did the same thing in the mountains. It was sputtering, backfiring then dying. I had to pull over several times and restat the car. I was finally able to get back home ok, But this time the check engine light came on and stayed on for several hours. Then finally went off.
The next day I took it into my mechanic who then ran other diagnostic tests. The computer scan revealed sodes po-171-fuel trim lean bank2, and po-174 fuel trim lean bank 1., and po461 fuel level sensor performance. They also ran what is called a smoke test. To see if the engine hoses had a leak. They did not.
The part that was replaced is called the MASS AIR FLOW SENSOR. a small plastic tube with a sensor in it.
I have since driven the car back and forth to the san francisco bay area without any problems. I hope this helps anyone with similar car problems.
Thank you,
Have a good day!