P0734: Gear 4 Incorrect Ratio
25 vehicles · 8 makes · $100-$12,000 repair
Most Reported On
P0734 is an OBD-II diagnostic trouble code meaning “Gear 4 Incorrect Ratio.” This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 4th gear. The module continuously compares input shaft speed to output shaft speed; if the ratio in 4th gear doesn't match the expected value, it sets P0734. This usually indicates the transmission is slipping or not fully engaging 4th gear due to a hydraulic, friction, or solenoid problem. Symptoms include slipping, flaring RPM, harsh or missed shifts, and possibly limp mode. This code is most commonly reported on 2007-2026 BMW X5, 2011-2026 BMW X3, and 2016-2021 BMW M2, plus 22 other vehicles, with repair costs ranging from $100 to $12,000.
Common Causes
Typical Repair Cost
Based on 29 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0734, 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 (25)
ZF 9-Speed Transmission Hesitation, Hard Shifts and Stalling (2016-2019 MDX)
1999 3.2TL 5-speed auto was the start of the famous Acura V6 transmission failures
3.0CL automatic transmission slips and fails — flush is forbidden, filter is not serviceable
Transfer Case Actuator Motor Failure
Transfer Case Actuator Motor Failure
DCT (M-DCT) Mechatronics Unit Failure
Transfer Case Actuator Motor Failure
Transfer Case Failure - xDrive Models E84/F48 X1
Aisin 8-Speed Transmission Jerking
xDrive Transfer Case Stress & Fluid Degradation - F98 X4 M / F98 X4 M
xDrive Transfer Case Stress & Fluid Degradation - F97 X3 M / F98 X4 M
Transfer Case Actuator Motor Failure (xDrive AWD System)
SMG III Hydraulic Pump Failure (M6 and SMG-Equipped 645Ci/650i)
DCT Dual-Clutch Transmission Shudder & Clutch Wear - F82/F83 M4
xDrive Transfer Case Actuator Motor Failure - E70/F85/F95 X5 M
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
Automatic Transmission No-Reverse / Failsafe Due to ZF 5HP19 Drum and Valve Body Wear
DCT Dual-Clutch Transmission Wear & Judder - F10 M5
DCT Dual-Clutch Transmission Shudder & Clutch Wear - F87 M2/M2C
SMG III Hydraulic Pump Failure - E60 M5
SMG Hydraulic Pump and Clutch Actuator Failure
FAQ
What does P0734 mean?
P0734 stands for "Gear 4 Incorrect Ratio." This code means the Transmission/Powertrain Control Module detected an incorrect gear ratio in 4th gear. The module continuously compares input shaft speed to output shaft speed; if the ratio in 4th gear doesn't match the expected value, it sets P0734. This usually indicates the transmission is slipping or not fully engaging 4th gear due to a hydraulic, friction, or solenoid problem. Symptoms include slipping, flaring RPM, harsh or missed shifts, and possibly limp mode.
What are the most common causes of P0734?
The most common causes of P0734 are: Low or degraded/burnt transmission fluid, Slipping clutch packs or worn friction elements in 4th gear, Stuck or faulty shift solenoid, Valve body / internal hydraulic leak or restriction, Worn or failing torque converter, Faulty input or output speed sensor, Internal mechanical wear (bands, planetary gears). The specific cause varies by vehicle.
How much does it cost to fix P0734?
Repair costs for P0734 range from $100 to $12,000, depending on the vehicle and root cause.
Which vehicles are affected by P0734?
Au7o has documented P0734 across 25 vehicle models from 8 manufacturers: Acura, BMW, Chrysler, GMC, Hyundai, Kia, Lincoln, Mercedes-Benz.
Sources (12)
- media2007 Hyundai Veracruz Automatic Transmission Problems - CarComplaints
- ForumBimmerpost X1 Forum - Transfer case actuator gear / xDrive malfunction discussion
- NHTSANHTSA Vehicle Page for 2018 BMW X2 - Complaints and Investigations
- TSBBMW Technical Service Bulletin GBSEL-SELP24 - Transmission Jerking and Delayed Reverse Engagement
- ForumReddit r/BMW Discussion: 2018 BMW X2 Transmission Jerking Problem
- ForumBimmerpost X3M/X4M Forum - Transfer case fluid service interval discussion for F97/F98
- articleHonda Class Action Alleges Transmission Defect (2016-2019 Acura MDX)
- articleAcura RDX, MDX and TLX Transmission and Infotainment System Defects
- Forum2017 MDX Advance sluggish & jerky ZF9 Transmission
- TSBTSB 23-2250 - 10R60/10R80/10R80 MHT Harsh/Delayed Engagement And/Or Shift (NHTSA)
- TSB10R60/10R80/10R80 MHT Automatic Transmission - 2021-2023 Ford & Lincoln (Ford OEMDTC)
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.