P0733: How to Diagnose & Fix — Gear 4 Incorrect Ratio
30 vehicles · 13 makes · $25-$12,000 repair
How to diagnose and fix P0733: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
BMW X3 · 2011–2026
The xDrive transfer case actuator in the X3 is a common failure item. The electric servo motor that controls torque distribution to the front axle wears out internally, causing drivetrain warning messages and loss of AWD capability. Common between 80,000-120,000 miles.
Common Symptoms
- Drivetrain malfunction warning message
- 4WD/xDrive warning light
- Loss of all-wheel drive engagement
- Grinding noise from center of vehicle
- Difficulty with traction in poor conditions
- Intermittent warning that clears on restart
How to Fix
Replace the transfer case actuator motor. Change the transfer case fluid at the same time. The actuator can be replaced without removing the entire transfer case. Rebuilt units are available at lower cost but OEM is recommended for reliability.
Sources for this issue (1)
BMW M2 · 2016–2021
The 7-speed M-DCT dual-clutch transmission in F87 M2 models can develop mechatronics unit failures, causing harsh shifting, failure to engage gears, or transmission fault warnings. The issue is related to the solenoid pack and hydraulic valve body within the mechatronics sleeve.
Common Symptoms
- Harsh or delayed shifts
- Transmission malfunction warning
- Failure to engage gear
- Grinding noise during shifts
- Limp mode activation
- Check engine light
- Jerking at low speeds
How to Fix
Replace or rebuild the mechatronics unit. In some cases, a transmission adaptation reset via ISTA can resolve early-stage symptoms. Severe cases require full mechatronics replacement, which involves dropping the transmission. Fluid change every 30k miles helps extend life.
Sources for this issue (1)
BMW X1 · 2013–2022
The xDrive transfer case actuator motor in X1 models can fail, causing loss of all-wheel drive functionality. The electric motor that engages the front axle wears out or its internal gears strip. Failure is often sudden and accompanied by drivetrain warning messages.
Common Symptoms
- Drivetrain malfunction warning on dashboard
- 4x4 warning light illuminated
- Loss of power to front wheels
- Grinding or clicking noise from under vehicle
- Vehicle feels unstable in slippery conditions
- Reduced traction in snow or rain
How to Fix
Replace the transfer case actuator motor (also called the servo motor). The transfer case itself usually does not need replacement. Ensure the transfer case fluid is changed at the same time. Some owners report success with rebuilt actuators at lower cost.
Sources for this issue (1)
Lincoln Aviator · 2020–2023
BMW X6 · 2008–2023
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P0733 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0733 mean?
P0733 stands for "Gear 4 Incorrect Ratio." This code indicates the transmission control module found that the actual gear ratio in 4th gear is outside the acceptable range for that gear. It is detected by comparing transmission input speed against output speed while 4th gear is engaged. A mismatch typically signals the transmission is slipping in 4th gear or that a control/hydraulic fault is preventing proper engagement.
What are the most common causes of P0733?
The most common causes of P0733 are: Low or contaminated transmission fluid, Worn 4th-gear clutch packs or bands, Failing shift solenoid for 4th gear, Valve body or line pressure issues, Internal transmission mechanical wear, Restricted transmission filter, Faulty input or output speed sensor. The specific cause varies by vehicle.
How much does it cost to fix P0733?
Repair costs for P0733 range from $25 to $12,000, depending on the vehicle and root cause.
Which vehicles are affected by P0733?
Au7o has documented P0733 across 30 vehicle models from 13 manufacturers: Acura, BMW, Chevrolet, Chrysler, Ford, Infiniti, Jeep, Kia, Lincoln, Mazda, Mercedes-Benz, Nissan, Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.