c5 PCM p1870 code
Thread Starter
Instructor
Joined: Jul 2025
Posts: 125
Likes: 4
From: San Marcos CA
c5 PCM p1870 code
Hello everyone, I've recently gotten my 2.73 diff on my a4 corvette swapped to a diff from a manual with the 3.42 gears in it. The diff is in proper working order and the car drives smooth and fun. However whenever i take the car on the highway for a bit and than come off the highway, my car throws the code p1870 and shifts extremely hard from 1st to 2nd gear. Coming off of the highway and downshifting from my higher gears is smooth and just fine. The strange part is that whenever i clear the code, the car drives perfectly normal again??? I had my transmission tuned by Excelsior Motorsports here in California and they mentioned that it might have to do with my TCC. But what's throwing me off is the fact that there's no lights on the dash, and clearing the code resolves the issue. any input would be greatly appreciated, Thank you!
Tech Contributor
Joined: Jan 2007
Posts: 19,388
Likes: 1,134
From: Dyer, IN
Hello everyone, I've recently gotten my 2.73 diff on my a4 corvette swapped to a diff from a manual with the 3.42 gears in it. The diff is in proper working order and the car drives smooth and fun. However whenever i take the car on the highway for a bit and than come off the highway, my car throws the code p1870 and shifts extremely hard from 1st to 2nd gear. Coming off of the highway and downshifting from my higher gears is smooth and just fine. The strange part is that whenever i clear the code, the car drives perfectly normal again??? I had my transmission tuned by Excelsior Motorsports here in California and they mentioned that it might have to do with my TCC. But what's throwing me off is the fact that there's no lights on the dash, and clearing the code resolves the issue. any input would be greatly appreciated, Thank you!
