P0729 on Chevrolet
Gear 6 Incorrect Ratio
P0729 on Chevrolet vehicles indicates gear 6 incorrect ratio. Au7o has documented this code across 1 Chevrolet model — most commonly on Silverado 1500. P0729 means the transmission control system detected an incorrect gear ratio in 6th gear — the computer compares input shaft speed to output shaft speed and found the resulting ratio doesn't match what 6th gear should produce. This usually indicates the transmission is slipping in that gear, a clutch or band isn't holding, or a hydraulic/solenoid control problem is preventing proper engagement. You may feel slipping, flaring RPM, harsh shifts, or the transmission dropping into limp mode. Low fluid and worn internal components are frequent contributors. Typical repair costs on Chevrolet range from $1,500 to $2,800, depending on the specific model and root cause.
Common Causes of P0729
- •Low or contaminated transmission fluid
- •Worn or slipping clutches/bands inside the transmission
- •Faulty shift solenoid or pressure control solenoid
- •Valve body wear or sticking valves
- •Failing torque converter
- •Internal mechanical wear or damage
- •Speed sensor fault giving incorrect ratio calculation
P0729 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.
Looking for P0729 on a different make?
View P0729 across all makes →Frequently Asked Questions
What does P0729 mean on Chevrolet?▼
P0729 stands for "Gear 6 Incorrect Ratio." P0729 means the transmission control system detected an incorrect gear ratio in 6th gear — the computer compares input shaft speed to output shaft speed and found the resulting ratio doesn't match what 6th gear should produce. This usually indicates the transmission is slipping in that gear, a clutch or band isn't holding, or a hydraulic/solenoid control problem is preventing proper engagement. You may feel slipping, flaring RPM, harsh shifts, or the transmission dropping into limp mode. Low fluid and worn internal components are frequent contributors. On Chevrolet specifically, this code is documented across 1 model.
What causes P0729 on Chevrolet vehicles?▼
Common causes on Chevrolet: Low or contaminated transmission fluid, Worn or slipping clutches/bands inside the transmission, Faulty shift solenoid or pressure control solenoid, Valve body wear or sticking valves, Failing torque converter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0729 on a Chevrolet?▼
Repair costs on Chevrolet range from $1,500 to $2,800, depending on the specific model and root cause.
Which Chevrolet models have P0729 documented?▼
Au7o has documented P0729 on 1 Chevrolet model: Silverado 1500.