P0729: Gear 6 Incorrect Ratio
7 vehicles · 6 makes · $150-$6,500 repair
Most Reported On
P0729 is an OBD-II diagnostic trouble code meaning “Gear 6 Incorrect Ratio.” P0729 means the transmission control system detected an incorrect gear ratio in 6th gear — the computer compares input shaft speed to output shaft speed and found the resulting ratio doesn't match what 6th gear should produce. This usually indicates the transmission is slipping in that gear, a clutch or band isn't holding, or a hydraulic/solenoid control problem is preventing proper engagement. You may feel slipping, flaring RPM, harsh shifts, or the transmission dropping into limp mode. Low fluid and worn internal components are frequent contributors. This code is most commonly reported on 2011-2019 Ford Fiesta, 2016-2019 Acura MDX, and 1994-2010 Chevrolet Silverado 1500, plus 4 other vehicles, with repair costs ranging from $150 to $6,500.
Common Causes
Typical Repair Cost
Based on 8 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0729, 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 (7)
DPS6 PowerShift Dual-Clutch Transmission Shudder, Slipping, and Failure
10R80 10-speed transmission harsh/erratic shifting and torque-converter shudder
6R80 6-Speed Automatic Harsh 1-2 Upshift / Erratic Shifting and Lead-Frame Solenoid Body Failure
FAQ
What does P0729 mean?
P0729 stands for "Gear 6 Incorrect Ratio." P0729 means the transmission control system detected an incorrect gear ratio in 6th gear — the computer compares input shaft speed to output shaft speed and found the resulting ratio doesn't match what 6th gear should produce. This usually indicates the transmission is slipping in that gear, a clutch or band isn't holding, or a hydraulic/solenoid control problem is preventing proper engagement. You may feel slipping, flaring RPM, harsh shifts, or the transmission dropping into limp mode. Low fluid and worn internal components are frequent contributors.
What are the most common causes of P0729?
The most common causes of P0729 are: Low or contaminated transmission fluid, Worn or slipping clutches/bands inside the transmission, Faulty shift solenoid or pressure control solenoid, Valve body wear or sticking valves, Failing torque converter, Internal mechanical wear or damage, Speed sensor fault giving incorrect ratio calculation. The specific cause varies by vehicle.
How much does it cost to fix P0729?
Repair costs for P0729 range from $150 to $6,500, depending on the vehicle and root cause.
Which vehicles are affected by P0729?
Au7o has documented P0729 across 7 vehicle models from 6 manufacturers: Acura, Chevrolet, Ford, Lincoln, Nissan, Volkswagen.
Sources (12)
- NHTSAFord Fiesta PowerShift Transmission NHTSA Complaints
- 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
- ForumSOLVED! - Sudden loss of 3rd/4th gear (4L60E) - GMTNation
- ForumTransmission slipping in 3rd gear - SilveradoSierra.com
- articleMost Common 4L60E Transmission Problems & How to Fix Them - Motorverso
- ForumFord F-150 10-Speed Transmission Lawsuit Over Harsh Shifting - CarComplaints.com
- TSBTECHNICAL SERVICE BULLETIN - 10R80 Harsh/Delayed Shifts (NHTSA TSB PDF)
- articleClass Action Filed Over Ford 10R80 Automatic Transmission Problems - ClassAction.org
- Forum09g keeps going into limp mode — VW Beetle Forum
- articleVolkswagen New Beetle Transmission Problems & Solutions
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.