check engine soon light

Hi,
I have a 99 Monte LS the only time the light comes on is when i fill up and go on the expressway. I have had it checked and the code is 1870, transmission component slipping, but when I had it checked at the mechanic he could find nothing. It has happened 3 times the exact same way and never in between, and it never comes back on until the same situation as above. Could it be still reading an old code problem that has been fixed or just the gas cap not tight enough???
Any advice out ther??
Thank you

It is not related to the gas cap.Something in the transmission is broken inside.Take it to a transmission shop that does very good work.

Hi,
I have a 99 Monte LS the only time the light comes on is when i fill up and go on the expressway. I have had it checked and the code is 1870, transmission component slipping, but when I had it checked at the mechanic he could find nothing. It has happened 3 times the exact same way and never in between, and it never comes back on until the same situation as above. Could it be still reading an old code problem that has been fixed or just the gas cap not tight enough???
Any advice out ther??
Thank you


Thanks for the reply, at least someone is able tell me there might be a real problem, all I was told is that it would be the gas cap.
Have a great day!
Sandee

sometimes the PO1870 is related to the torque converter clutch not engaging when it is supposed to. You may notice the tach is reading a few hundred rpm's more than normal just before the light is illuminated. The problem usually exists in the valvebody inside the transmission. Somewhat of a costly repair at any transmission shop.

Or you can drop the pan and replace the vavle body seal whick could cause this! I would also try a new vacuum module for the tranny! You can find it by fallowing the vac lines under the stock air box

sometimes the PO1870 is related to the torque converter clutch not engaging when it is supposed to. You may notice the tach is reading a few hundred rpm's more than normal just before the light is illuminated. The problem usually exists in the valvebody inside the transmission. Somewhat of a costly repair at any transmission shop.


I have had the car checked for the 2nd time, there was not anything to be found. I told them that the code was checked and it was a transmission code and they stil said they can't find anything wrong.
No engine codes came up at all, none in memory either.????
The car seems to run fine, didn't notice the rpm's though. No light came back on since.
I lost???

Or you can drop the pan and replace the vavle body seal whick could cause this! I would also try a new vacuum module for the tranny! You can find it by fallowing the vac lines under the stock air box

This sounds interesting, since it is only doing this occassionally, but I wouldn't be able to do it myself.
I might have this checked.

well if you had the code checked before, it was probably cleared of all codes. if the problem has not happened since this, then the computer wouldn't have any stored codes.

I dont believe the 700r4 trans has a mudulator valve on it so it shouldnt be that ,,the code is reffering to the trans going into overdrive prematuraly,,this may be able to be fixed by simply adjusting the detent cable to allow more mph or more rpms before it locks up into overdrive.

the majority of Monte Carlos used the 4L60E transmission and the PO1870 is a very intermittent code. The code usually doesn't set until the car has been in a "cruise" situation for some time and all requirements are met to lock up the torque converter. It is then that the computer will throw a code if it does not see that the converter clutch is locking up. There is a GM bulletin on the PO1870 and it goes into more detail on the code and the proper repair to fix the problem.

You can probley do this yourself but you need to take EXTREME care to make sure everything is put back just right! But you will need the service manuals and those cost a bit!

People do sell the repair kits for this but buying from GM on this one is really the only way to go!

OR you can replace the tranny with a used one! Will probley cost you no more the $500 for the tranny! and if you do the work yourself you will learn alot and save money...but stress might get to you!

If you lived around MN I would offer to do the work for you!

I dont believe the 700r4 trans has a mudulator valve on it so it shouldnt be that ,,the code is reffering to the trans going into overdrive prematuraly,,this may be able to be fixed by simply adjusting the detent cable to allow more mph or more rpms before it locks up into overdrive.

I brought my car with me and moved to Tennessee, the engine light did come on after the car was cruising for awhile. So far, it has been coming on and off in between trips while driving, but after a couple of times, went off by itself. Though nothing seems to be feeling any different, the rpms do go a little higher when it does come on.
Maybe someone down here can help me out.
Thanks for the advice.
Sandee

the majority of Monte Carlos used the 4L60E transmission and the PO1870 is a very intermittent code. The code usually doesn't set until the car has been in a "cruise" situation for some time and all requirements are met to lock up the torque converter. It is then that the computer will throw a code if it does not see that the converter clutch is locking up. There is a GM bulletin on the PO1870 and it goes into more detail on the code and the proper repair to fix the problem.

I will take a look at this, and hopefully get this fixed right. It's a really nice car, but I begin to worry if someone car figure out how to fix it!!
Thanks for the advice.
Sandee

I will take a look at this, and hopefully get this fixed right. It's a really nice car, but I begin to worry if someone car figure out how to fix it!!
Thanks for the advice.
Sandee

I have been told by an honest transmission specialist that sometimes the code is triggered by a sensor that's misreading the condition. It may not be serious at all, but it would be good to get it checked out. Usually, if something is wrong, it's in the valve body but doens't mean the whole transmission needs to be rebuilt. Beware of the less-than-totally honest mechanics!

I have been told by an honest transmission specialist that sometimes the code is triggered by a sensor that's misreading the condition. It may not be serious at all, but it would be good to get it checked out. Usually, if something is wrong, it's in the valve body but doens't mean the whole transmission needs to be rebuilt. Beware of the less-than-totally honest mechanics!

I have had the car over a year, it has been checked twice, but nothing was found. It has not changed in the way it's driving or handling in any way, I am pretty sure I would have noticed if it did get worse by now.Maybe it is faulty, especially if the light would go off on it's own.
I hope nothing more serious will be found.
Thanks for the advice,
Sandee

I have the same car, but not the same problem. My problem has always been with the fuel injectors getting clogged and having to have the spark plugs cleaned and recapped (3 times between 40K and 125K). Anyways, if the mechanic can't find anything wrong, take it to someone else or consider that the sensor could be bad. I am tired of hearing that crap that the gas cap may not be on tight. Are they charging you to check the code and see why the check engine light is on? Autozone does it for free as long as the check engine light is on when they hook up the code reader.... By the way, you can reset all the codes by simply disconnecting the battery and reconnecting it.

Hi,
I have a 99 Monte LS the only time the light comes on is when i fill up and go on the expressway. I have had it checked and the code is 1870, transmission component slipping, but when I had it checked at the mechanic he could find nothing. It has happened 3 times the exact same way and never in between, and it never comes back on until the same situation as above. Could it be still reading an old code problem that has been fixed or just the gas cap not tight enough???
Any advice out ther??
Thank you

I have the same car, but not the same problem. My problem has always been with the fuel injectors getting clogged and having to have the spark plugs cleaned and recapped (3 times between 40K and 125K). Anyways, if the mechanic can't find anything wrong, take it to someone else or consider that the sensor could be bad. I am tired of hearing that crap that the gas cap may not be on tight. Are they charging you to check the code and see why the check engine light is on? Autozone does it for free as long as the check engine light is on when they hook up the code reader.... By the way, you can reset all the codes by simply disconnecting the battery and reconnecting it.

I have had to pay twice for the car to be checked. But since the light has gone off by itself after a while by itself, I haven't taken it anywhere else. I would be tempted to have it checked if the it wasn't running good, but really, there doesn't seem to be anything different about the way it drives at all.I did have it turned off at Autozone, thankfully there is one in this small town!! Thanks for the info on the battery thing, though, that something I didn't know.

No problem. Disconnecting the battery only clears the codes out; the light could pop back on again if the sensor detects something wrong.


I have had to pay twice for the car to be checked. But since the light has gone off by itself after a while by itself, I haven't taken it anywhere else. I would be tempted to have it checked if the it wasn't running good, but really, there doesn't seem to be anything different about the way it drives at all.I did have it turned off at Autozone, thankfully there is one in this small town!! Thanks for the info on the battery thing, though, that something I didn't know.

No problem. Disconnecting the battery only clears the codes out; the light could pop back on again if the sensor detects something wrong.

Your right about that!! I will have it checked at a transmission shop here and hopefully they don't find anything or, as suggested, valve repair.
I just have to be careful who I take it to.
Thanks.