OBD-II Code · Transmission
P0730
Incorrect Gear Ratio
Severity
critical
Highest on our scale. Expect major repair cost if it is ignored.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$500–$4,000
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
The transmission isn't achieving the commanded gear ratio.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Slipping
- Harsh shifts
- Limp mode
Likely causes
- Worn clutchesMost common
- Low fluid
- Failed solenoid
- Internal wear
Read the full diagnostic procedureP0730 means the TCM has calculated an actual gear ratio (input RPM ÷ output RPM) that doesn't match any of the commanded ratios for the gear it think…
P0730 means the TCM has calculated an actual gear ratio (input RPM ÷ output RPM) that doesn't match any of the commanded ratios for the gear it thinks it should be in, but the TCM can't tell which gear specifically is wrong — so it sets the generic 'incorrect ratio' code.
This is the canary in the coal mine for internal trans wear
clutch slippage, band wear, a stuck pressure-control solenoid letting line pressure droop, or fluid-level/quality problems aerating the pump. Fluid check is non-negotiable here — burned or low fluid is the cause more often than any single internal component on a P0730. Once fluid is verified, the next live-data check is line pressure with a gauge tap'd into the test port: at idle in DRIVE most automatics want 60-90 psi; at wide-open throttle in 1st you want to see 180-240 psi depending on application. Low line pressure under load with good fluid points to the pressure-control solenoid (cheap external fix) or to internal seal leakage (rebuild territory). Note that a slipping torque converter clutch can mimic P0730 by creating an apparent ratio mismatch even when the gearset is fine — that's why P0741 has to be ruled out before condemning hard parts.
Vehicle-specific patterns2003-2010 Honda Accord/Odyssey V6 5AT is the textbook P0730 vehicle — the 3rd gear clutch pack wears out, the trans slips, ratio math goes wrong, and…
- 2003-2010Honda Accord/Odyssey V6 5AT is the textbook P0730 vehicle — the 3rd gear clutch pack wears out, the trans slips, ratio math goes wrong, and Honda issued multiple TSBs and a class-action settlement on certain VIN ranges (BAYA/MGFA codes); fluid changes early extended life but rebuilds are common past 130k miles.
- 2004-2008Chrysler/Dodge with the 42RLE (Wrangler, Liberty, 300) throws P0730 from a failed overdrive solenoid causing the overdrive band not to apply — external solenoid fix, not a rebuild.
- 2007-2013GM 6L80 throws P0730 when the 3-5-Reverse waveplate fractures (a known internal failure mode) — this one IS a rebuild.
- 2006-2012Ford with the 6R80 (F-150, Expedition) commonly throws P0730 from a stuck pressure-control solenoid in the lead-frame; a $400 solenoid body swap fixes what would otherwise look like a rebuild.
Estimated repair$250 (external solenoid + filter) to $4,800+ (full rebuild on the Honda 5AT).
Look up another code
P0730 — frequently asked
What does a P0730 code mean?
The transmission isn't achieving the commanded gear ratio.
What causes a P0730 code?
Common causes: Worn clutches; Low fluid; Failed solenoid; Internal wear.
What are the symptoms of a P0730 code?
Typical symptoms: Check engine light; Slipping; Harsh shifts; Limp mode.
Is it safe to drive with a P0730 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $500-$4,000.
How do I diagnose a P0730 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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