2000 GMC Sierra Engine code P1870

MIA AL

MEMBER
2000 GMC SIERRA
V8
2WD
AUTOMATIC
220,000 MILES

On a 2000 GMC Sierra after diving 30 miles, the transmission shift violently between 1st and 2nd gear (consistent at 10 mph) check engine light turns on. If I dive the truck locally (short trips) the Trans shift great no problems. The transmission has always been service per manufactures recommendation the fluid level fine no visible leaks. A buddy of mine has a code scanner and for six months it’s always the same code. P1870 manufactures control transmission.

1 Reply

MISSY2977

MEMBER
1 POST

I have a 2000 GMC Sierra 4 wheel drive and I had mine to a garage and that 1870 code is a valve in the transmission that needs to be replaced. My truck does the same exact thing. Once it's been driven on highway after a while it shifts hard the first 2 gears. If you shut the truck off for 5 to 10 minutes and start it back up, it should go away for a little while. Mine does!