P1870 on Chevrolet
Transmission Component Slipping
P1870 on Chevrolet vehicles indicates transmission component slipping. Au7o has documented this code across 3 Chevrolet models — most commonly on Silverado 1500, Suburban, Tahoe. 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 Chevrolet range from $1,500 to $3,500, 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 Chevrolet by Model
Chevrolet Silverado 1500(1 issue)
- 4L60E Automatic Transmission 3-4 Clutch Pack and Sun Shell Failure (Slipping, Loss of 3rd/4th Gear)1994-2010
The 4L60E 4-speed automatic behind the half-ton Silverado is notorious for wearing out its 3-4 clutch pack and cracking the input 'sun shell' (reaction sun gear shell) as mileage climbs. Owners report the truck suddenly loses 3rd and 4th gear (revs up but won't pull) while reverse and low gears still work, or a hard grinding/no-move with a fractured sun shell. The 3-4 clutch is the known weak point and often burns up first; the larger input drum on 2004-and-up units also likes to crack internally. This is one of the single most-searched failures for these trucks.
Chevrolet Suburban(1 issue)
- 4L60E Transmission 3-4 Clutch Failure / Loss of 3rd & 4th1994-2006
The 4L60E automatic behind the half-ton Suburban is notorious for burning up the 3-4 clutch pack. The 3-4 apply circuit is long and loses pressure as valve-body bores wear, so the clutches overheat and glaze. Symptoms are slipping in 3rd/4th, a jump from 2nd straight to 4th, or a sudden loss of 3rd and 4th (RPM flares, no forward pull in higher gears while reverse and low gears still work). On 2004+ units the input drum can also crack, and the pot-metal sun-gear shell ("sun shell") strips teeth, causing loss of reverse.
Chevrolet Tahoe(2 issues)
- 4L60E Automatic Transmission 3-4 Clutch Failure (Loss of 3rd/4th Gear)1995-2010
The 4L60E 4-speed automatic behind the Vortec V8s is the single most common major failure on high-mileage Tahoes. The 3-4 clutch pack is the known weak point: its friction plates burn up, and the truck suddenly slips or drops out of 3rd and 4th gear (RPMs flare with no acceleration), leaving effectively only 1st and 2nd. Later-production units (roughly 2004+) used thinner/cheaper clutch material and tend to fail earlier. Contributing factors include worn shift solenoids, a leaking valve body/accumulator, TCC solenoid failure, and neglected/burnt fluid. Many owners hit this between 120k-180k miles.
- 4L60E transmission loss of reverse (cracked sun shell / worn lo-reverse clutches)1995-1999
The 4L60E automatic behind the 5.7L is prone to losing reverse (and sometimes 2nd) as it ages. The classic root cause is the reaction sun shell ("sunshell") cracking or stripping its splines, along with worn lo-reverse clutches. Slipping typically appears first in reverse and worsens until reverse is gone entirely; a fractured sunshell can also take out 2nd. The 1995 model is a transition year whose transmission does not directly interchange, so a rebuild is generally the only route for those trucks.
Looking for P1870 on a different make?
View P1870 across all makes →Frequently Asked Questions
What does P1870 mean on Chevrolet?▼
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 Chevrolet specifically, this code is documented across 3 models.
What causes P1870 on Chevrolet vehicles?▼
Common causes on Chevrolet: 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 Chevrolet?▼
Repair costs on Chevrolet range from $1,500 to $3,500, depending on the specific model and root cause.
Which Chevrolet models have P1870 documented?▼
Au7o has documented P1870 on 3 Chevrolet models: Silverado 1500, Suburban, Tahoe.