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I have a 1998 Buick Century Custom with a 3.1 V6 engine With 99,500 miles. My Service Engine light came on & it has a code P1870 which from what I have read indicates transmission slippage. I took the car to a transmission shop & the technician took it for a road test using his hand held computer analyzer.
everything checked out ok so he reset the code & told me to continue driving it & to bring it back if the trouble returned. After driving about 700 miles the light came back on & has the same P1870 code. I have not had the transmission serviced so I asked if he thought that might cure my problem & he told me it would probably a waste of money & if the trouble came back it would probably need rebuilding at a cost of $1800.00 The transmission operates perfectly. Do you think a transmission service might cure the problem.
Thanks,
Robert Joyner  

most the time codes for this car are 1811 max shift adapt, 1870 is most common 4l60e transmission in chevy trucks but this code sets when no lock up clutch is lowing rpms.does your transmission satrt shifting more firm when let is on?  

Thanks or your reply

No I cannot see any difference in the way the transmission shifts when the
light is on. It seems to shifft perfectly to me. I do believe that I was told that the transmission is a 4T60e
Bobby12333  

could be a bad lock up solenoid, also internal issue with torque converter
you need the scan tool to see live data stream to see what going on during lock up.  

Bobby12333
Your transmission is a 4T60e  Not a 4L60 e  (Truck) as discribed in a Prior Post...
You could have a bad Lock up solonoid. or more common  bad / Failed / Shrunk O- ring to Feed lock up . Converters are not a common failure . But the Rubber  / O-rings and seals are  High Failure Components,
also the  sealing rings and bushings play a Major part in sealing this problem , and it all really does tend  to point to a soft parts overhaul  
Hog Rider

HOG I didnt say he had a 4l60 e What I said was the 1870 code was more common with 4l60e, I diffently know the difference, are we going to have another pissing contest?4t65e in this car is more common than 4t60e thats what I was pointing toward. your an a** hole hog lets disagree on said codes your answer in most caes I've seen is get the codes and I'll see what I can do if you have the years behind the bench you state you do  then you should be able to know what going on without the code in most case's

can be stuck lock up valve or solenoid, and can be checked with side cover removed and valve body off, most shop will want to rebuild with high mileage.  

AIRWORLD2
YOU Call me an A** Hole  again and I,ll  Go out of my way to make your life Miserable ....  I Have Never Called YOU an ***  Thats Wrong  Bro !!!!!!!!!!!!!  
Hog Rider

be careful what you type, I called you a word and not making a threat towards you.
I am here and you dont worrie me I'm a bit older and I would guess much wiser than you.
re read my post and you will find that I said the code was more common in trucks not the car he was asking about....And your an A&& Hole and I would square off with you or anyone else thats what these board and others are for!!!!!!!!!    
By the way for those who will read this I've been doing transmission repair since 1978, I own my shop,and my family has another transmission shop and have a third store that we also sell hard parts.
When I do reply to question I have a good reason to do so.

From a 1950 to a 2006 I  have had them in my bays, and have other shops that call on me and I call on them for tech answers. I have a data base for repairs I have found that are not in most repair manuals I have been keeping since I bought my first computer in 1989 long before most shops that I know even used them.  

That Was Still Wrong  To Call Me An As***hole
If Your Older and Wiser than Me  Act IT ....
Or Go away.........
And If your in a Family Busniess  Why would you Call  Rebuliders (That only want to help others ) Cuss words ???
What if  a Family man wanted to deal with You ? and he had his Child with him ?  and you spoke like that to another ???  
Hog Rider

hog, if you cant handle heat get out of kitchen. I dont call my customer's A@@ hole.And I wouldn't talk in that manner to someone that didnt come off like they know things, but answer's questions with other questions. this is all speculation on our part as we cant test drive the vechicle and sometime the owners and driver's interpert things that aren't always transmission issues.sometimes  years of seeing the same problem over and over is the best knowlege to have, the scanners are great tools but not all things are found by the sacnner's.  

i agree airworld.. not all things are found with scanners..im great with my hands.. and good with tools.. and just like mr. bobby i have the same issue with my transmission.. which is a 97 4t60e.. 4t65e replaced 4t60e in 98.. im haveing the same issue as mr bobby .. but no code at all.. plenty of power in first.. but the shift from 1-2 feels like its tryin to snatch the transmission out .. its a heavy hard shift.. 2-3 is rough but not as bad.. and 3-4 is kinda smooth.. down shiftin ..small issue.. just a lil rough... quite frankly .. i just have no friggin idea what to do next..  

Its been my experience that an 1870 code  usually requires an overhaul.If the problem didnt originate in the convertor it most likely damaged the convertor.700 miles is a long time for that code to reset the only way to be sure your fixing it is to overhaul the trans.you could drive it with a scanner on data stream and watch the RAMP.I forgot what each letter means but the RAMP is the difference in rpms between the crankshaft of the engine and the input shaft of the trans.The computer controls RAMP by applying various pressures to the converter clutch The scanner should tell you what the actual RAMP is and what the desired RAMP is.When the actual RAMP is to high for what the computer is commanding it sets the code.  

I too,, have a 1998 Buick Century Custom with a 3.1 V6 engine With 115,000 miles. My Service Engine light came on & it has a code P1870 which from what I was told by aamco tech, indicates that while in 4th gear, and tcc engaged, the ecm has detected transmission slippage. when comparing the input shaft speed to the output shaft speed. and I have foamy bubbles in the fluid on the dip stick, which to me suggest that I have air mixing with the fluid , but the level is good, not even the slightest bit low or over full and the color is slightly red tint .
 Is it me , or do I need to have big money ?  

first thing to do is clear the code.disconnect the neg batt cable and hold the brake pedal down for 20 seconds then reconnect the battery.Then drive the car.The quicker the code comes back the more serious your problem is.It basically comes down to how long you want to keep the car.A Aamco rebuild is going to run you $2500 to $3500 depending how aggressive the manager is.I would keep driving it.When it goes completly
then make a decision.At that point let Aamco take it apart and then haggle with them.
Your car is pretty old they will come down in price if you threaten to give them the title and walk away.And if the light is on dont forget to clear the code before you go in for your annual inspection.  

The light always goes out after awhile and then don't come on for like a month then on a long trip to families ( about 2 hrs. ) it will come on for a couple of days and then go out again . The fellow at AutoZone says it might help if I change the fluid and filter I t might prolong the inevitable. Although I do feel a hard shift from first into second but that is usually during high rpm speed gain entering the freeway .
But it's the bubbles that get me, seems it sucking in air from somewhere. What's your opinion about the fluid/filter change , should I try it or would it be a waste of 48 dollars ?