P1870 on Pontiac
Transmission Component Slipping
P1870 on Pontiac vehicles indicates transmission component slipping. Au7o has documented this code across 1 Pontiac model — most commonly on Grand Prix. This manufacturer-specific code (common on GM and Ford automatics, e.g. 4L60E) means the computer detected slippage between transmission components, most often at the torque converter clutch, where commanded engagement does not match actual behavior. When it sets, the PCM typically raises line pressure to protect the transmission and may lock out the converter clutch. Symptoms include harsh or delayed shifts, RPM flare/slipping, and reduced fuel economy. It often points to a worn valve body bore or TCC components and should be addressed before further internal damage occurs. Typical repair costs on Pontiac range from $2,300 to $2,700, depending on the specific model and root cause.
Common Causes of P1870
- •Worn torque converter clutch (TCC) regulator valve bore in the valve body
- •Faulty TCC solenoid or PWM solenoid
- •Worn or failing torque converter clutch
- •Low or degraded transmission fluid
- •Worn internal clutches or seals (e.g., input shaft O-ring)
- •Worn valve body / internal hydraulic leak
P1870 on Pontiac by Model
Pontiac Grand Prix(1 issue)
- 4T65-E Automatic Transmission Hard Shifting and Failure2001-2008
The 4T65-E (and 4T65-E HD on the LS4 V8 GXP) automatic transmission commonly develops harsh/erratic shifting and eventual failure as mileage climbs. Causes include worn clutch packs, weak accumulator springs allowing slow shifts that trigger maximum line pressure, failing pressure control or shift solenoids, and the 4T65E-HD pan-magnet/line-pressure issue. Outright failure can leave the vehicle stranded with no warning.
Looking for P1870 on a different make?
View P1870 across all makes →Frequently Asked Questions
What does P1870 mean on Pontiac?▼
P1870 stands for "Transmission Component Slipping." This manufacturer-specific code (common on GM and Ford automatics, e.g. 4L60E) means the computer detected slippage between transmission components, most often at the torque converter clutch, where commanded engagement does not match actual behavior. When it sets, the PCM typically raises line pressure to protect the transmission and may lock out the converter clutch. Symptoms include harsh or delayed shifts, RPM flare/slipping, and reduced fuel economy. It often points to a worn valve body bore or TCC components and should be addressed before further internal damage occurs. On Pontiac specifically, this code is documented across 1 model.
What causes P1870 on Pontiac vehicles?▼
Common causes on Pontiac: Worn torque converter clutch (TCC) regulator valve bore in the valve body, Faulty TCC solenoid or PWM solenoid, Worn or failing torque converter clutch, Low or degraded transmission fluid, Worn internal clutches or seals (e.g., input shaft O-ring). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P1870 on a Pontiac?▼
Repair costs on Pontiac range from $2,300 to $2,700, depending on the specific model and root cause.
Which Pontiac models have P1870 documented?▼
Au7o has documented P1870 on 1 Pontiac model: Grand Prix.