P0730: Incorrect Gear Ratio
The transmission computer sees a mismatch between input and output shaft speeds that does not match any correct gear, which usually means slipping.
What P0730 means
The transmission computer always knows which gear it has commanded and what ratio that gear should produce. It divides input shaft speed by output shaft speed to measure the actual ratio. RepairPal explains that P0730 means the computer sees more than the allowed RPM difference between the two, either during shifts or at steady speed, and that it often implies slipping. When a clutch pack or band cannot hold, the engine spins faster than it should for the road speed. Low or burnt fluid is a common and cheaper cause, while worn clutches, a weak pump, failed solenoids, a valve body problem or a torque converter fault point to bigger repairs. A faulty speed sensor can also produce a false incorrect ratio reading. KBB warns that it can turn into a severe problem quickly. Shops check fluid, read gear specific codes, look at live input and output speeds and line pressure, and decide whether solenoid or valve body work will fix it or the transmission needs a rebuild.
Common symptoms
- Check engine light on
- Slipping, with engine revs rising but little acceleration
- Delayed or harsh shifts
- Transmission in limp mode
- Burning smell from the fluid
Most common causes
- Low or burnt transmission fluid
- Worn clutches or bands inside the transmission
- Faulty shift solenoid or pressure control solenoid
- Clogged filter or valve body problem
- Faulty input or output speed sensor
- Torque converter problem
What to check yourself first
Check the fluid level and condition right away. Dark, burnt smelling fluid or metal particles on the dipstick point to internal wear. Note which gear or shift slips, since the shop will want to know.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Transmission fluid change | $294-$356 | Low or burnt fluid causes many transmission codes. Check the correct fluid type for your transmission. |
| Transmission filter and fluid service | $621-$785 | Helps if the filter is clogged, but will not fix worn clutches. |
| Transmission diagnosis with a full scan | $125-$183 | A transmission scan reads the codes stored in the transmission computer, which a basic reader may miss. |
| Replace transmission (if internally damaged) | $6,238-$6,764 | If internal clutches are worn out, a rebuilt or replacement transmission is the fix. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0731 Gear 1 Incorrect Ratio
- P0732 Gear 2 Incorrect Ratio
- P0733 Gear 3 Incorrect Ratio
- P0700 Transmission Control System (MIL Request)
- P0715 Input/Turbine Speed Sensor "A" Circuit