P0732 on GMC
Gear 3 Incorrect Ratio
P0732 on GMC vehicles indicates gear 3 incorrect ratio. Au7o has documented this code across 1 GMC model — most commonly on Sierra 1500. This code means the transmission control module detected that the gear ratio in 3rd gear does not match what it expects when the transmission is commanded into that gear. The computer compares input (turbine) speed to output shaft speed; if the math for 3rd gear is wrong, it sets this code. It usually points to internal slipping or a hydraulic/electronic control fault rather than a sensor reading error. Typical repair costs on GMC range from $1,800 to $3,500, depending on the specific model and root cause.
Common Causes of P0732
- •Low or dirty/degraded transmission fluid
- •Worn clutch packs or friction material in 3rd gear circuit
- •Faulty shift solenoid for 3rd gear
- •Valve body or pressure control problems
- •Internal mechanical wear or damage in the transmission
- •Clogged transmission filter restricting flow
- •Faulty input/output speed sensor giving skewed data
P0732 on GMC by Model
GMC Sierra 1500(1 issue)
- 4L60-E / 4L65-E Sun Shell Failure Causing Loss of Reverse and 2nd/4th Gear2000-2007
On GMT800 Sierra 1500 trucks equipped with the 4L60-E family automatic, a well-known internal failure is cracking or stripping of the reaction sun shell. Owners commonly report sudden loss of reverse, no 2nd gear, no 4th gear, or a truck that starts in 3rd gear after a bang or flare. This is widely documented in transmission rebuild literature, repair databases, and owner reports for GM trucks and SUVs using this transmission.
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What does P0732 mean on GMC?▼
P0732 stands for "Gear 3 Incorrect Ratio." This code means the transmission control module detected that the gear ratio in 3rd gear does not match what it expects when the transmission is commanded into that gear. The computer compares input (turbine) speed to output shaft speed; if the math for 3rd gear is wrong, it sets this code. It usually points to internal slipping or a hydraulic/electronic control fault rather than a sensor reading error. On GMC specifically, this code is documented across 1 model.
What causes P0732 on GMC vehicles?▼
Common causes on GMC: Low or dirty/degraded transmission fluid, Worn clutch packs or friction material in 3rd gear circuit, Faulty shift solenoid for 3rd gear, Valve body or pressure control problems, Internal mechanical wear or damage in the transmission. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0732 on a GMC?▼
Repair costs on GMC range from $1,800 to $3,500, depending on the specific model and root cause.
Which GMC models have P0732 documented?▼
Au7o has documented P0732 on 1 GMC model: Sierra 1500.