1999 Saturn SL1 Transmission Issue

I have a 1999 Saturn SL1 with a transmission issue. After driving in stop an go traffic and the trans warms up, it doesn’t want to change gears from second to third. I can remedy this if i put the car in neutral, turn it off and back on will continue to run for a bit longer. The longer I’m in stop and go traffic, the more frequent I have to do this. On the highway this is a different story and I can stay in the last gear and drive forever! Also after being in traffic for so long, if I put the car into reverse, I have to lightly feather the gas until it slowly goes into gear.

The last issue which I think might be related is that the idle will sometimes stay extremely high if I put my car into neutral at red lights, which I do often to avoid have to turn the car off and on again to reset the transmission.

Any help you could provide would be greatly appreciated.

When is the last time you had the transmission fluid changed? That would be the first thing to try if you haven’t had it done in the last few years.

Do not take it to a quick-lube place or transmissjon repair chain. Take it to a trusted local mechanic. If you don’t have one, find one near you in the “Mechanics Files” section of this site.

Then if fresh fluid doesn’t help, you can try one of the additives mentioned in this thread:

And if an additive doesn’t help, then you’re looking at a transmission rebuild or replacing it with another used one.

Thanks for the recommendations. I had the fluid changed last year, so I should be good to go on that front. I read an article where someone had the same issue I had and was recommended to check and or change the TPS, ECTS, and or the CPS sensor. Would you know if this would help and what these do? Thanks.

When something resets when shutting down, it would point to an electrical issue but you really need to get the computers scanned by a competent mechanic who can evaluate any trouble codes.

My daughters 2002, 35k miles transmission symptoms, fluid and filter change fixed all!

You are probably going to need a valve body. This isn’t too hard if you have some mechanical skills and basic tools.


A little trick that sometimes works on Saturn’s is called the reverse slam procedure. It won’t cost you anything to try. Set the hand brake and run the engine with the transmission in reverse gear for about a half to a full hour. It cleans out the valve body. The name comes from using this to cure the issue of the transmission shifting harshly going between drive and reverse gear.

TPS - throttle position sensor. It tells the computer how much you have pressed on the gas

ECTS - engine coolant temperature sensor. It tells the computer how hot the engine coolant is.

CPS - crankshaft position sensor. Tells the ignition system when to fire the next spark plug.

Of those, the tps and ects might be related to the high idle problem. When a cps fails, it usually either causes the car not to start, or causes misfires. This doesn’t seem related to your symptoms, so I’d discount that one as a potential cause.

Does your dashboard temp gauge seem to be acting normally, showing the same coolant temp as it always has when the engine is fully warmed up? On cars of that era there’s usually some kind of idle air control gadget (IAC) and those tend to gum up over time. Cleaning that might be all you need for high idle problem. If not that, other types of high idle problems tend to be complicated to diagnose.

No one asked but, this IS an automatic, isn’t it? If its a manual, there are 4 plastic bushings on the shift rail inside the trans and one has probably failed. It won’t shift into 3rd or won’t stay in 3rd, for a 5 speed manual. Disregard and listen to the other posters if its an auto-box.

Just noticed the high idle, that’s not related to the shift problems as the transmission is shifted electronically. The high idle is most likely a bad intake manifold gasket. This is a common problem on the SL1 engine. If you have this replaced, do not use an OEM gasket, use an aftermarket gasket from felpro, the hold up much better.

The manifold gasket is a quick check, use some type of spray around the intake manifold gasket at the top, outboard corner around the #1 cylinder. This is where they fail. All you are looking for when you spray this area is for the idle to change somehow. If it changes at all, then that means that what you are spraying is getting into the manifold. I usually use a carb cleaner but wd40 works pretty good for this as well.

BTW, this usually causes the check engine light to come on with the code P0509.

One more thing, it may not seem like it right now, but the Saturn is a very reliable car. I had no trouble putting 275k on mine, but I did have to replace the intake manifold gasket twice, the second time I learned about using the felpro so I didn’t have any more trouble out of it after that.

The TPS and CPS are pretty reliable as well. Most of the time when someone changes either, they find out that that wasn’t the problem. But the ECTS can be problematic. GM used a plastic tipped ETCS on some of the cars and they were prone to cracking. If you have a problem with this, be sure to replace it with a brass tipped ECTS, I was lucky, never had a problem with mine.

The EGR can clog up on you and have to be cleaned out, but that can happen with any car, had to clean mine once. This is not your current problem though.

Thanks for the recommendations. It is an automatic transmission. I’m going to have the filter and fluid replaced again and will post the ERR code later that it is generating.