P0731: Gear 1 Incorrect Ratio
28 vehicles · 7 makes · $100-$12,000 repair
Most Reported On
P0731 is an OBD-II diagnostic trouble code meaning “Gear 1 Incorrect Ratio.” The transmission is not achieving the correct gear ratio in 1st gear. This code is most commonly reported on 2005-2014 Mercedes-Benz CLS-Class (CLS350, CLS500, CLS550, CLS63 AMG), 2017-2023 Mercedes-Benz GLS (GLS450, GLS580), and 2016-2023 Mercedes-Benz Metris (Cargo, Passenger), plus 25 other vehicles, with repair costs ranging from $100 to $12,000.
Common Causes
Typical Repair Cost
Based on 32 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0731, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Vehicles Affected (28)
Multitronic CVT Transmission Failure
Automatic Transmission Harsh Shifting
CVT Multitronic Transmission Failure and PRNDS Flashing on Front-Wheel-Drive A4
Multitronic CVT Transmission Failure
Transfer Case Actuator Motor Failure
Transfer Case Actuator Motor Failure
DCT (M-DCT) Mechatronics Unit Failure
Transfer Case Actuator Motor Failure
xDrive Transfer Case Stress & Fluid Degradation - F97 X3 M / F98 X4 M
SMG Hydraulic Pump and Clutch Actuator Failure
SMG III Hydraulic Pump Failure - E60 M5
Transfer Case Actuator Motor Failure (xDrive AWD System)
DCT Dual-Clutch Transmission Shudder & Clutch Wear - F82/F83 M4
DCT Dual-Clutch Transmission Shudder & Clutch Wear - F87 M2/M2C
Transfer Case Failure - xDrive Models E84/F48 X1
ZF 8HP Transmission Mechatronic Issues (All 8 Series & M8)
Transfer Case Actuator Motor Failure (All xDrive Models)
ZF 6HP Transmission Mechatronic Sleeve & Valve Body Failure
SMG III Hydraulic Pump Failure (M6 and SMG-Equipped 645Ci/650i)
Automatic Transmission No-Reverse / Failsafe Due to ZF 5HP19 Drum and Valve Body Wear
DCT Dual-Clutch Transmission Wear & Judder - F10 M5
xDrive Transfer Case Actuator Motor Failure - E70/F85/F95 X5 M
Aisin 8-Speed Transmission Jerking
xDrive Transfer Case Stress & Fluid Degradation - F98 X4 M / F98 X4 M
FAQ
What does P0731 mean?
P0731 stands for "Gear 1 Incorrect Ratio." The transmission is not achieving the correct gear ratio in 1st gear.
What are the most common causes of P0731?
The most common causes of P0731 are: Worn 1st gear clutch pack, Low line pressure, Failed shift solenoid, Valve body issue, Internal seal failure. The specific cause varies by vehicle.
How much does it cost to fix P0731?
Repair costs for P0731 range from $100 to $12,000, depending on the vehicle and root cause.
Which vehicles are affected by P0731?
Au7o has documented P0731 across 28 vehicle models from 7 manufacturers: Acura, Audi, BMW, Chrysler, Ford, Mercedes-Benz, Nissan.
Sources (12)
- mediaMB Medic: 722.9 7G-Tronic Valve Body & Conductor Plate Must Read
- manufacturerECU Testing: Mercedes 7G-Tronic TCM conductor plate failure
- ForumBenzWorld: 722.9 7G Will Valve Body Fail cause Clutch Wear/Fail?
- otherCarComplaints: Mercedes 722.9 7G-Tronic Transmission Problems Cause Lawsuit
- manufacturerIscanTech: Mercedes-Benz 7G Transmission Removing Valve Body
- ForumBenzWorld: Problem with the 7G-tronic on my CLS350
- ForumBimmerpost X3M/X4M Forum - Transfer case fluid change interval discussion for F97/F98
- NHTSANHTSA Vehicle Page for 2007 BMW M6 - includes complaints and investigations related to SMG transmission issues
- videoYouTube Repair Video by 'BMW Repair Guide': Replacing SMG Hydraulic Pump on BMW M6 E63
- NHTSANHTSA Complaint #10406933 - 2006 BMW M5 transmission/SMG failure
- NHTSANHTSA Complaint #10416359 - 2006 Audi A6 transmission failure/loss of drive
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.