P0731 Transmission computer sees the wrong speed ratio in first gear

Gear 1 incorrect ratio

P0731 in short

P0731 means the transmission computer measured input and output speeds that do not match first gear, so first is slipping or not engaging properly. Bulletins point to worn clutches, speed sensor faults and software. Have it inspected soon, and check for a bulletin for your vehicle before agreeing to a rebuild.

The transmission computer knows which gear it has asked for and reads the speed going in and the speed coming out. If the two speeds do not match the ratio of gear one, the gear is slipping or not fully engaged, and the computer sets this code.

Makers trace P0731 to several different things. Ram replaces the K1 clutch and input shaft on some heavy-duty trucks, Ford covers a speed sensor in the 6R80 wiring frame on older F-150s and lists it among the 10R80 shift codes, and Ram and Hyundai have software updates.

A real slipping gear is a shop repair, but the cheapest first step is a bulletin check by VIN and a scan for other codes.

Most likely causes

  1. Worn or damaged clutch for first gear

    Supported by vehicle data
    Why it ranks here
    FCA replaces the K1 clutch and input shaft, or repairs its snap ring, on 2019–2023 Ram heavy-duty trucks that set P0731.
    What would change this
    Rises on a covered Ram 3500/4500/5500, or if a shop sees first gear slip under load.

  2. Input or output speed sensor giving a false reading

    Possible — needs testing
    Why it ranks here
    The ratio is worked out from speed sensor signals, so a bad sensor or connection can make a healthy gear look wrong. Ford ties an output speed sensor fault in the 6R80 leadframe to P0731.
    What would change this
    Rises if a speed sensor code is also stored or a sensor reading drops out on the scan tool.

  3. Shift solenoid or valve body problem (Ford 10R80)

    Supported by vehicle data
    Why it ranks here
    Ford lists P0731 alongside shift solenoid codes for harsh or delayed shifts on 10R80 trucks and SUVs.
    What would change this
    Rises on a covered Ford with harsh or delayed shifts and solenoid codes together.

  4. Transmission computer software

    Supported by vehicle data
    Why it ranks here
    Ram and Hyundai address P0731 on some models with a transmission computer update.
    What would change this
    Rises on a covered 2016 Ram 1500 or 2020–2021 Accent that has not had the update.
    How to test the transmission control module (tcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read codes from the engine and transmission modules with a scan tool that supports both, before anything is cleared. Note every code, not just this one.

    Low riskTool: scan tool that reads the transmission module

  2. Check for a P0731 bulletin or software update for your VIN at a dealer or on the NHTSA site.

    Low risk

  3. Have a transmission shop watch commanded gear, input speed and output speed on a scan tool during a road test.

    Best left to a shopTool: scan tool with transmission data and output controls

    Warning:Shop test. It is done while driving or on a lift, often with pressure gauges, and needs the maker's procedure.

Symptoms

  • Check engine light, sometimes with no other symptom
  • Harsh or delayed engagement or shifts
  • Loss of power or a flare in engine speed when pulling away Gets more serious: stop and have it checked.
  • Transmission stuck in one gear (limp-home mode) Gets more serious: stop and have it checked.

How to fix

  1. Do not clear the code before the transmission module has been read.

  2. Ask a dealer whether your VIN has an open P0731 bulletin or software update. Ram, Ford and Hyundai have issued them.

Parts and cost context

  • Transmission control module (TCM):Do not replace the module for P0731 unless a test points to it. Several bulletins are software updates to the existing module, and others fix parts inside the transmission.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ford

  • 2011–2013 · F-150

    Supported by vehicle data

    Ford 19N01-S3 extends coverage on the 6R80 leadframe, where an output speed sensor failure can set P0731. Later 10R80 F-150s are named in TSB 23-2123 and 24-2252 for harsh or delayed shifts with gear ratio codes. The bulletins are on NHTSA, but whether they are still current is not verified, so it is labelled vehicle data rather than confirmed.

    Where it is:Inside the transmission, in the wiring frame on the valve body

  • 2020–2023 · Explorer

    Supported by vehicle data

    Ford TSB 24-2252 lists P0731 among the codes with harsh or delayed shifts on the 10R80 MHT. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • 19N01-S3Status unverified

    6R80 molded leadframe extended coverage

    2011–2013f-150, expedition · issued · NHTSA 10183669

    An output shaft speed sensor failure in the leadframe can light the MIL with codes including P0731. Covers the 2011–2013 F-150 and 2012–2013 Expedition and Navigator. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • TSB 24-2252Status unverified

    10R80 MHT harsh or delayed engagements and shifts with MIL

    2020–2023f-150, explorer · issued · NHTSA 11006770

    Lists shift solenoid and gear ratio codes, including P0731–P0734, with harsh or delayed engagements and shifts. Covers the 2020–2023 Explorer and Aviator and the 2021–2023 F-150. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • TSB 23-2123Status unverified

    10R80 harsh engagement, harsh or delayed shift, possible MIL

    2017–2023f-150, expedition, mustang, ranger · issued · NHTSA 10234596

    Covers 2017–2020 F-150, 2018–2021 Expedition, Navigator and Mustang, and 2019–2023 Ranger with the 10R80. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ram

  • 2019–2023 · 3500

    Supported by vehicle data

    FCA 21-051-24 replaces the K1 clutch and input shaft when P0731 is set, and 21-002-23 repairs the K1 clutch drum snap ring on 2022–2023 trucks. The 4500 and 5500 are also covered. The bulletins are on NHTSA, but whether they are still current is not verified, so it is labelled vehicle data rather than confirmed.

    Where it is:Inside the transmission

  • 2016 · 1500

    Supported by vehicle data

    FCA 21-010-20 updates the transmission computer software. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • 21-051-24Status unverified

    Replace K1 clutch / input shaft assembly for P0731

    2019–20233500, 4500, 5500 · issued · NHTSA 11008221

    Applies when the MIL is on and P0731-00 (gear 1 incorrect ratio) is set. The repair replaces the K1 clutch and input shaft assembly. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 21-002-23Status unverified

    K1 clutch snap ring repair

    2022–20233500, 4500 · issued · NHTSA 10231775

    Replaces the K1 clutch drum snap ring and possibly the K1 input shaft drum after a MIL with P0731. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 21-010-20Status unverified

    Transmission computer software update

    20161500 · issued · NHTSA 10173369

    Reprograms the transmission computer after a MIL with transmission codes. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Cadillac

  • 2000–2001 · Deville

    Supported by vehicle data

    GM 010730009A covers an intermittent no-power condition with P0731 or P0732 on the 4T80-E. The Eldorado and Seville are also covered. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • 010730009AStatus unverified

    Intermittent no power with P0731 and/or P0732, 4T80-E

    2000–2001deville, eldorado, seville · issued · NHTSA 619719

    Some Hydra-Matic 4T80-E transmissions may lose drive intermittently and set P0731 and/or P0732. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Hyundai

  • 2020–2021 · Accent

    Supported by vehicle data

    Hyundai 24-01-014H covers a warning light with P0731 among other transmission codes. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • 24-01-014HStatus unverified

    Warning light with TCU codes including P0731

    2020–2021accent · issued · NHTSA 10251288

    Covers TCU codes P0730, P0731, P0741, P0867 and P1603 and refers to a separate procedure. Only the NHTSA flat-file summary was reviewed, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0700Transmission module requests the check engine light

    Primary / secondary Possible — needs testing

    Likely primary: P0731. On cars with a separate transmission module, a basic code reader may show only P0700, which means the module has stored its own code. P0731 can be that code, so fix P0731 and P0700 goes with it.

  • P0732Transmission computer sees the wrong speed ratio in second gear

    Shares causes Supported by vehicle data

    GM tied P0731 and P0732 together to an intermittent no-power condition on the 4T80-E, and Ford lists both among its 10R80 shift codes.

  • P0733Transmission computer sees the wrong speed ratio in third gear

    Same system Possible — needs testing

    Both are gear ratio checks on the same transmission, for different gears.

  • P0734Transmission computer sees the wrong speed ratio in fourth gear

    Same system Possible — needs testing

    Both are gear ratio checks on the same transmission, for different gears.

All Transmission codes

P0731 questions

Does P0731 mean my transmission is shot?

Not necessarily. Some bulletins fix it with a speed sensor or a software update. Others replace one clutch pack rather than the whole transmission. Get a bulletin check and a road test first.

Is it safe to drive with P0731?

Have it inspected soon. Toyota tells owners to get the car checked right away when the light is on for the transmission, and a slipping first gear can leave you without power when pulling out.

Why does a gear code come with a speed sensor code?

The computer works out the ratio from speed sensors. If one reads wrong, a gear can look like it is slipping when it is not.

Sources and review

  1. Toyota Camry Owner's Manual (OM06291U) — Toyota
  2. Cal. Code Regs. Tit. 13, § 1968.2 — Malfunction and Diagnostic System Requirements (OBD II) — California Air Resources Board (via Cornell LII)
  3. FCA 21-051-24: Replace K1 clutch / input shaft assembly, Ram 3500/4500/5500 — FCA US LLC / NHTSA ,
  4. FCA 21-002-23: K1 clutch snap ring repair, 2022–2023 Ram 3500/4500 — FCA US LLC / NHTSA ,
  5. Tranny Problems: On the Outside Looking In — MOTOR Magazine ,
  6. Ford 19N01-S3: 6R80 molded leadframe extended coverage, 2011–2013 F-150 and 2012–2013 Expedition/Navigator — Ford Motor Company / NHTSA ,
  7. Ford TSB 24-2252: 10R80 MHT harsh/delayed engagements or shifts with MIL and shift solenoid / gear ratio DTCs — Ford Motor Company / NHTSA ,
  8. Ford TSB 23-2123: 10R80 harsh engagement, harsh or delayed shift, possible MIL — Ford Motor Company / NHTSA ,
  9. FCA 21-010-20: TCM software update, 2016 Ram 1500 — FCA US LLC / NHTSA ,
  10. Hyundai 24-01-014H: Warning light with TCU codes including P0731, 2020–2021 Accent — Hyundai Motor America / NHTSA ,
  11. DTC P0700 — Saab 9-5 (9650) 2010 Workshop Information System — SaabWISOnline (community rehost of Saab/GM service information)
  12. GM 010730009A: Intermittent no power with P0731 / P0732, 4T80-E — General Motors / NHTSA ,
  13. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
Last reviewed
Written by
Saurabh K.
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