# Code p1870

**URL:** <https://community.cartalk.com/t/code-p1870/32030>\
**Category:** Maintenance/Repairs\
**Tags:** transmissions\
**Created:** [June 18, 2009, 8:37am UTC](https://community.cartalk.com/t/code-p1870/32030 "2009-06-18T08:37:39Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![1navyguy](https://avatars.discourse-cdn.com/v4/letter/1/f0a364/32.png) [@1navyguy](https://community.cartalk.com/u/1navyguy)\
**Post date:** [June 18, 2009, 8:37am UTC](https://community.cartalk.com/t/code-p1870/32030/1 "2009-06-18T08:37:39Z")

</div>

I have a 1996 Grand prix with 165000 miles. at about 150000 or so the trans died and I had it replaced with a used one. The car was off the road for a year or so and was never used or even started. I recently put it back on the road and the first thing I did was drive it 1400 miles. There was some initial trans fluid leaking. I check the trans fluid several times a week and always look at the spot I have been parked at for signs of leaks but haven’t seen any and the fluid level looks good. Now I drive it daily (about 100 miles a day) mostly highway miles and the SES light is on all the time and the code I get is p1870 which means there is some sort of “slipage” going on in the trans. I have a reader and have cleared the code but after about 20-30 miles the light comes back on. I feel no slipage at all and it seems to shift fine, no hard/late/early shifting. I’ve been told it could be simple like 1 or both solenoids (think they are on the side of the trans) but no one can tell me for sure. Please HELP!!!

---

<div class="post-metadata">

**Author:** ![vtcodger2](https://avatars.discourse-cdn.com/v4/letter/v/e68b1a/32.png) [@vtcodger2](https://community.cartalk.com/u/vtcodger2)\
**Post date:** [June 18, 2009, 11:10am UTC](https://community.cartalk.com/t/code-p1870/32030/2 "2009-06-18T11:10:03Z")

</div>

This link might be useful: [http://www.automotivehelper.com/topic557446.htm](http://www.automotivehelper.com/topic557446.htm) If you get far enough into it, there is a description of exactly when/why P1870 is set on a slightly younger Pontiac. One caveat. P1870 is a manufacturer defined code. It means whatever GM wants it to mean and can (but probably won’t) change between models or brands.