1999 Saturn SC1 High Idle After Driving

He gave you good advice. The coolant temperaure sensor (ECTS) are known problems on the 1.9 liter engines. They were updated to a better design by Saturn in 2001 if I remember correctly.

Should be around $20.00 for the updated brass tipped sensor (ECTS) from the dealer. Just about as easy to install as a spark plug.

https://www.2carpros.com/forum/saturn-sc-1-1995-vt4925.html

Good luck and let us know. :)

Hi! Thanks for the tip! I went to Saturn and picked up a temperature sensor for $19.01 including tax. I had my dad put it on Thursday evening. It seems that it didn't fix it. I didn't drive much this weekend, but when I was driving to work this morning, it started doing it. When I got off the interstate after driving about 17 miles, it was idling at around 2000 RPM. When I came to a complete stop, it went back down to normal. It seems that I have to be completely stopped before it will idle back down. It won't idle down if I go as slow as 5 MPH. I don't know much about cars, but it sounds like a speed sensor or something like that. Any more ideas?

Glad you replaced the ECTS. Buy dad a beer for sure. :) Even tho it did not correct your issue it willl save you future grief. With the old style plastic tipped ECTS it was not a matter of if it would fail but only when.

Good for you taking responsibility for keeping your car running right. Researching problems and seeing that something is done about them is a trait that will serve you well all youir life. Don't be afraid to get your hands dirty with dad. You will learn even more. Wish my dad was still here. God rest his soul.

Now that high idle issue. Did you disconnect the negative battery cable while replacing the ECTS. Computers will need to relearn with the new part. Also check with dad on the condition of the connection for the ECTS. When that plastic tip cracks it can leak very small amounts of coolant that can corrode the connection. Sometimes they can be cleaned and other times they must be replaced. Pricey little piece of plastic and wire tho. About $30..00 dealer only item.

You can save some money ordering online for dealer only saturn parts if you order several items together. If not the shipping and handing will eat you alive. www.saturnparts.net is one such online dealer. there are several others.

The other thing to consider for the high idle would be a gunked up throttle body and a dirty IAC (idle air control) valve and port. I would recommend cleaning both with carb cleaner and an old toothbrush. I like to remove the throttle body to clean it. It is easier in the long run and especially facillitates cleaning the IAC and it's port which is part of the throttle body. This is something that should be done as preventetive maintenence anyway. So I would do it one way or the other. The IAC can also fail but more often is just dirty. Don't loose the $11.00 dealer only o-ring that seals the IAC valve. Reuse it with a thin film of vaseline when it is reinstalled.

I would clean the EGR valve and it's port at the same time. Good PM also. Have a gasket for the throttle body and EGR valve on hand. You can reuse the old ones if they are in good shape but for the small cost why bother.

Good luck and let us know. :)