P0731: Gear 1 Incorrect Ratio
Key takeaways
- P0731 means the transmission computer compared input and output shaft speeds in first gear and the ratio didn't match what first gear should give.
- The usual feel is a slip, flare or delayed takeoff from a stop; many cars also go into limp mode.
- Check fluid level and condition first, then shift solenoids and the valve body; worn clutches inside the transmission come last.
- Ford, Ram, Hyundai, Jeep and Nissan have bulletins naming P0731, from software updates to an internal thrust washer failure on 2024 Ram heavy-duty trucks.
- Fixes range from about $100 for a software update to $3,000–$5,500 for a rebuilt or replacement transmission.
What P0731 means
Your transmission isn’t turning at the speed it should in first gear, which usually means something is slipping. Scanners call it Gear 1 Incorrect Ratio. The transmission computer knows the exact ratio first gear should give. It reads the input shaft speed (or engine speed) and the output shaft speed, divides one by the other, and when the result stays outside its limit while first gear is commanded, it stores P0731. Most often that means a clutch or band isn’t holding. Sometimes one of the speed signals is wrong and nothing is slipping at all.
Is it safe to drive?
Short trips, gently, to get it diagnosed. Many cars go into limp mode with P0731 and hold one gear, so takeoffs feel slow and the engine revs high. The bigger issue is heat: a slipping clutch burns its lining and cooks the fluid, and that damages the rest of the transmission. What changes the answer: the engine flares in rpm without the car moving, the car won’t pull away from a stop, or the fluid smells burnt. Any of those, stop driving and have it towed.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Low, old or burnt fluid | Level and condition on the dipstick or check plug; leaks underneath | $20–$100 top up; $150–$300 fluid service |
| Software needing an update | A bulletin covers your make, model and year | $100–$200 |
| Faulty speed sensor or wiring making a false ratio | Input or output speed drops out in live data; codes like P0715 or P0720 alongside | $100–$300 sensor; $100–$250 wiring |
| Sticking shift solenoid or valve body | Solenoid codes, harsh or late shifts, pressure test | $300–$1,200 |
| Worn first-gear clutch, band or internal part | Slip persists with good fluid, sensors and software; debris in the pan | $3,000–$5,500 rebuild or replacement |
What to check first
- Check the fluid. Level with the procedure for your car (many need a hot check at idle), then color and smell. Red or pink and clean is good; brown, black or burnt is not. Red drips underneath? See the red fluid leak guide.
- Look for a bulletin on your exact car before buying parts.
- Read all transmission codes. A speed sensor or solenoid code stored with P0731 changes the diagnosis.
- Watch the live data on a test drive. A shop compares input and output speeds in first gear. A true slip shows as a flare; a sensor fault shows as a dropout or a jumpy reading.
- Only then pressure test and pull the pan. Clutch material and metal in the pan point to internal wear.
- Don’t clear it and drive as a fix. The code returns on the next hard takeoff if the slip is real.
The bulletins show two patterns. Hyundai (2020–2022 Venue) and Ford (10-speed 10R60/10R80 trucks and SUVs with harsh or delayed shifts) lean on software and service procedures, and the Hyundai bulletin allows replacing the transmission if the update doesn’t fix it. Ram’s 2024 2500 and 3500 bulletins name a failed rear selective thrust washer, which is internal.
What it costs
The cheap outcome is a software update or fluid service at $100–$300. The common outcome is a solenoid or valve body repair at $300–$1,200. The expensive outcome is worn clutches and a rebuilt or replacement transmission at $3,000–$5,500. Paying for a proper transmission scan and test drive first is how you avoid a rebuild quote for what turns out to be a sensor. If it also jerks when accelerating, tell the shop. Need help reading your other codes? Ask our AI mechanic.
Related codes
P0731 often comes with P0730 (general ratio fault) or ratio codes for other gears such as P0732 and P0733; several gears at once points toward fluid, pressure or a shared clutch. On some cars the engine computer also shows P0700, which only flags that the transmission module has a code. 36 complaints filed with NHTSA mention P0731, led by the Ford F-150 with 13; a complaint is an owner report, not a confirmed cause.
What owners report to NHTSA
36 complaints filed with NHTSA mention P0731, 32 of them since 2015, across 15 different models. The component owners most often filed it under: power train.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| FORD F-150 | 13 | 2011, 2012, 2013, 2014, 2015 |
| RAM 3500 | 6 | 2022 |
| FORD ESCAPE | 3 | 2014, 2016, 2017 |
Manufacturer service bulletins that name P0731
88 technical service bulletins and manufacturer communications filed with NHTSA mention P0731, from 9 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- HYUNDAI VENUE (2020, 2021, 2026), bulletin 10233540: Certain 2020-22MY Venue (QX) vehicles may experience a check engine light or malfunction indicator light due to Diagnostic Trouble Codes (DTC) listed below. Perform the TCU update, and, if necessary, replace the IVT (Int…
- RAM 3500 (2024), bulletin 11009478: "Rear Selective Thrust Washer Failure Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): P0218-00 - Tr…
- RAM 2500 (2024), bulletin 11010661: "Rear Selective Thrust Washer Failure Customers may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may exhibit/set one or more of the following DTCs: P0218-00 - Transmission High Temperature O…
- FORD EXPEDITION (2018, 2019, 2020, 2021), bulletin 10234596: Some 2017-2020 F-150, 2018-2021 Expedition/Navigator/Mustang and 2019-2023 Ranger vehicles equipped with a 10R80 automatic transmission may exhibit a harsh engagement/harsh shift/delayed shift. It is possible the vehicle…
- LINCOLN NAVIGATOR (2018, 2019, 2020, 2021), bulletin 10236680: Some 2017-2023 F-150, 2018-2023 Expedition/Navigator/Mustang, 2019-2023 Ranger, 2020-2023 Explorer/Aviator/Transit and 2021-2023 Bronco vehicles equipped with a 10R60 transmission and built on or before 23-Dec-2022 or wi…
- FORD TRANSIT (2020, 2021, 2022, 2023), bulletin 10236680: Some 2017-2023 F-150, 2018-2023 Expedition/Navigator/Mustang, 2019-2023 Ranger, 2020-2023 Explorer/Aviator/Transit and 2021-2023 Bronco vehicles equipped with a 10R60 transmission and built on or before 23-Dec-2022 or wi…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Can low transmission fluid cause P0731?
Yes, and it's the first thing to check. Clutches are applied by fluid pressure, so low or worn-out fluid lets first gear slip and the ratio drifts. Topping up and fixing the leak solves some cases, but if the fluid is burnt the clutches may already be damaged.
Does P0731 mean my transmission is shot?
Not always. A software update, a sticking solenoid, a valve body problem or even a bad speed sensor can set it. Internal clutch wear is the expensive answer, and a shop should rule out the cheaper ones before quoting a rebuild.
Can I drive with P0731?
Short trips, gently, to get it looked at. A slipping clutch makes heat, and heat wears the rest of the transmission. If it slips badly, won't pull away, or the fluid smells burnt, have it towed.
What's the difference between P0731 and P0730?
P0730 is the general incorrect gear ratio code; P0731 narrows it to first gear. The gear it names helps a shop work out which clutch, band or solenoid is involved.