P0731 on Cadillac
Gear 1 Incorrect Ratio
P0731 on Cadillac vehicles indicates gear 1 incorrect ratio. Au7o has documented this code across 1 Cadillac model — most commonly on DeVille. This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 1st gear. The module compares input (engine/turbine) speed to output shaft speed; when the car is commanded into 1st but the calculated ratio doesn't match the expected value, P0731 sets. This points to slipping, an incorrect shift, or a hydraulic/mechanical problem rather than just an electrical fault. You may feel slipping, harsh or delayed engagement, or the transmission may go into a limited 'limp' mode. Typical repair costs on Cadillac range from $600 to $4,000, depending on the specific model and root cause.
Common Causes of P0731
- •Low or degraded/burnt transmission fluid
- •Slipping clutch packs or worn friction components
- •Stuck or faulty shift solenoid affecting 1st gear
- •Internal hydraulic leak / valve body fault
- •Worn or failing torque converter
- •Faulty input or output speed sensor
- •Mechanical wear (planetary gears, bands) inside the transmission
P0731 on Cadillac by Model
Cadillac DeVille(1 issue)
- 4T80-E Lower Valve Body and Fourth-Gear Clutch Failure Causes Slipping and Lost Overdrive1994-2005
The 4T80-E four-speed used behind the Northstar develops two documented and related faults. The lower control valve body and its channel plate/gasket leak internal pressure, producing 1-2 shift delays, slips and flares with P0731 or P0732, and slipping or complete loss of fourth gear with P0734. Where the pressure loss has been present for a while, the fourth-gear (overdrive) clutch pack cooks off its friction material - owners report finding the pan full of clutch debris and the fourth clutch stripped bare. The transmission fluid pressure switch assembly sets similar codes and is a cheaper first suspect. Owners also report the plastic locating ears on the valve body breaking. Fluid contaminated with clutch material is what carries the failure across the rest of the clutch packs, which is why a late fluid change on a slipping unit often makes it worse rather than better.
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What does P0731 mean on Cadillac?▼
P0731 stands for "Gear 1 Incorrect Ratio." This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 1st gear. The module compares input (engine/turbine) speed to output shaft speed; when the car is commanded into 1st but the calculated ratio doesn't match the expected value, P0731 sets. This points to slipping, an incorrect shift, or a hydraulic/mechanical problem rather than just an electrical fault. You may feel slipping, harsh or delayed engagement, or the transmission may go into a limited 'limp' mode. On Cadillac specifically, this code is documented across 1 model.
What causes P0731 on Cadillac vehicles?▼
Common causes on Cadillac: Low or degraded/burnt transmission fluid, Slipping clutch packs or worn friction components, Stuck or faulty shift solenoid affecting 1st gear, Internal hydraulic leak / valve body fault, Worn or failing torque converter. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0731 on a Cadillac?▼
Repair costs on Cadillac range from $600 to $4,000, depending on the specific model and root cause.
Which Cadillac models have P0731 documented?▼
Au7o has documented P0731 on 1 Cadillac model: DeVille.