P0729 code meaning
Gear 6 Incorrect Ratio
Powertrain system Generic code P07xx codes Check engine light
What P0729 means
The transmission module divides input (turbine) speed by output speed and compares the result with the ratio of the commanded gear; a deviation means slip – a clutch or brake not holding, too little pressure – or a wrong gear. Thresholds: Ford more than 30 rpm off for 1.8 s three times (diesel 2023: over 20 % for 12 s), GM's 2006 tables and the Allison 1000 converter slip of 200–230 rpm for 2.25 s after one trip, Saab's Aisin boxes over 20 % twelve times without MIL. P0729 concerns sixth gear. Saab's Aisin six-speed also checks whether the actual ratio matches fourth or fifth – the sixth gear clutch is not holding and the box drops into another gear. Ford stores it only if the fault does not fit a particular solenoid (otherwise P0751 ff). On GM manual transmissions (LT4) it checks the gear position sensor instead.
P0729 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 14 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0729
- Slipping or flare in sixth gear, engine speed higher than expected
- Harsh or delayed shifts
- Limp mode (Aisin: second gear and reverse only), transmission warning
- Check engine light depending on manufacturer
Common causes of P0729
- Most likelyFluid level too low or fluid worn or contaminated
- Most likelyClutch for sixth gear worn (linings, piston seal)
- PossibleSticking shift or pressure valve, leaking valve body gasket, blocked passages
- PossibleGM manual transmissions only: gear position sensor faulty or not learned
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Transmission clutchesTransmission valve bodyTransmission fluidTransmission control module
What each part of P0729 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 29 | The exact fault in that area. |
What to do next
- Note P0729 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0729
What does P0729 mean?
P0729 means "Gear 6 Incorrect Ratio". The transmission module divides input (turbine) speed by output speed and compares the result with the ratio of the commanded gear; a deviation means slip – a clutch or brake not holding, too little pressure – or a wrong gear. It is a generic code, so it means the same on every make.
Is it safe to drive with P0729?
Drive gently and only to a workshop. With P0729 the car can go into limp mode (reduced power) to protect itself.
Will P0729 fail an emissions test?
Yes, it can. P0729 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0729 to fix?
Difficulty: hard. A typical repair takes 1 to 14 hours of work. This is a job for a workshop.
Will P0729 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.