My mileage has really taken a hit lately. My ECU is throwing a P0171. Another thread suggested checking the engine coolant sensor. Anyone know where that is located on a 99 2.5rs? Is there an ohm or voltage reading I should get off it? With the car cold not running I read 17ohms. Also lately I have noticed my cooling fan running when I get home from work. This seems odd with my 2 mile drive and the recent temperature outside.
i'm not really sure where the CTS is but the fan running has sort of the opposite cause of a faulty CTS, usually the sensor will cause a rich condition causing poor milage, but the car should runn a little cooler if anything, are you running your defrost when you are driving to and from work? what was your before milage and what is your after milage? have you changed plugs lately?
My mileage is never really very good with my short trips. I usually get around 21mpg, which doesn't seem that bad with my 2 mile trips and occasional longer driving. I get gas about every 5-6 weeks. Based on my last tank I am getting about 16mpg. I changed the plugs, fuel filter, pcv, wires, vacuum hoses, new clamps on the larger vacuum line when I purchased the car about 3000 miles ago. I use my defroster occasionally but I don't leave it on.
coolant temp sensor is in the crossover underneath the intake manifold, a failing temp sensor would make it run really rich, also extremely hard to start when cold, try taking the vaccume line off your fuel pressure regulator while the car is running, if fuel comes out you found your mileage problem
