P0729

Gear 6 Incorrect Ratio

Q: Is it safe to drive with P0729?

No — a slipping gear can overheat and damage the transmission fast. Minimize driving until it's repaired.

Q: Can I just clear P0729?

It returns quickly while the ratio stays wrong; the underlying fluid, solenoid, or mechanical fault has to be fixed.

Transmission gear ratio Generic OBD-II High

What it means

P0729 means the transmission control module measured an incorrect ratio between input and output speed in 6th gear — the gear is slipping or not engaging as commanded. It often stems from low fluid, a faulty shift solenoid, or worn internal clutches, and continued driving risks overheating and further transmission damage.

High

Can I keep driving? Drive as little as possible — an incorrect gear ratio means the transmission is slipping or not holding 6th, which can worsen quickly and cause overheating or damage.

Real-world scan data

Seen in

101

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Appears alongside · share of P0729 scans

P0735in 68.3% of scans

P0734in 59.4% of scans

P0732in 55.5% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Slipping or flaring when 6th gear should engage
Harsh, delayed, or erratic shifting
Unable to shift into or hold 6th gear
Hesitation or jerking on acceleration
Check-engine light on

Common causes

Most likely first

Low or degraded transmission fluidLikely
Worn clutches or internal transmission wearCommon
Faulty or stuck shift solenoidCommon
Faulty transmission control moduleLess often

How to diagnose & fix

Work through it in order

Scan and read freeze-frame, checking for companion solenoid or speed-sensor codes.
Check the transmission fluid level and condition first.
Test the shift solenoids and pressure control per service data.
Inspect for internal wear (clutch/band) if solenoids and fluid are good.
Repair or overhaul as indicated; replace the TCM only after mechanical causes are ruled out.

FAQ

Quick answers

Is it safe to drive with P0729?+

No — a slipping gear can overheat and damage the transmission fast. Minimize driving until it's repaired.

Can I just clear P0729?+

It returns quickly while the ratio stays wrong; the underlying fluid, solenoid, or mechanical fault has to be fixed.

Read & clear P0729 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX