Gear 6 Incorrect Ratio
The P0729 code means the vehicle's onboard diagnostic system has detected: Gear 6 Incorrect Ratio. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $200 - $3,000 (parts and labor)
Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.
Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.
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What Are the Symptoms of P0729?
- Check Engine Light on
- Transmission slipping in 6th gear
- RPM flare during 6th gear engagement
- Harsh shifting into or out of 6th gear
What Causes P0729? (Most Likely First)
- Worn 6th gear clutch pack or band Very High
- Low transmission fluid level or contaminated fluid High
- Faulty shift solenoid affecting 6th gear Moderate
- Internal transmission mechanical wear Moderate
Can I Still Drive with P0729?
Short distances only. P0729 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does incorrect gear ratio mean?
The TCM calculates the gear ratio by comparing input shaft speed to output shaft speed. When the actual ratio does not match the expected ratio for 6th gear, it means the clutches or band for that gear are slipping, causing power loss.
Can low fluid cause P0729?
Yes. Low transmission fluid reduces hydraulic pressure, which can cause clutch packs to slip. Check the fluid level first as it is the simplest and least expensive potential fix.
Is P0729 a sign the transmission needs rebuilding?
Not necessarily. While worn clutch packs require a rebuild, the issue may be a faulty solenoid or low fluid. Proper diagnosis can determine if the problem is electrical, hydraulic, or mechanical before committing to a rebuild.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P0729?
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Check transmission fluid level and condition; dark or burnt fluid indicates internal wear
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Monitor 6th gear ratio with a scan tool by comparing input and output shaft speeds
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Test shift solenoids related to 6th gear engagement with a scan tool
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Perform a transmission line pressure test in 6th gear to check for internal pressure loss
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
P0729 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Which Vehicles Commonly Get P0729?
- 2010-2020 Ford F-150 6R80 transmission
- 2012-2019 Chevrolet Silverado 6L80 transmission
- 2011-2020 Toyota Camry U760E transmission
- 2009-2019 Honda Accord 6-speed automatic
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