P0734 Transmission computer sees the wrong speed ratio in fourth gear

Gear 4 incorrect ratio

P0734 in short

P0734 means the transmission computer measured input and output speeds that do not match fourth gear, so fourth is slipping or not engaging. Bulletins point to a failed clutch or worn band on some Fords and to software on some Ram, Dodge and Kia models. Have it inspected soon and check for bulletins.

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 four, the gear is slipping or not fully engaged, and the computer sets this code.

Ford traced P0734 to a failed direct clutch on 2008–2013 F-150s and similar models, and to overdrive band wear on 1999 Taurus and Windstar. FCA and Kia address it on some 2014–2015 models with software.

Fourth is often an overdrive or cruising gear, so the first sign may be high engine speed on the highway.

Most likely causes

  1. Failed direct clutch (Ford 4R75E family)

    Supported by vehicle data
    Why it ranks here
    Ford ties slipping in third or no fourth, with P0733 or P0734, to direct clutch failure on 2008–2013 F-150, E-Series and Crown Victoria.
    What would change this
    Rises on a covered Ford with no fourth gear or slipping in third.

  2. Worn overdrive band (Ford AX4S)

    Supported by vehicle data
    Why it ranks here
    Ford links P0734, a flashing transmission lamp and no 3-4 shift to overdrive band wear on the 1999 Taurus and Windstar.
    What would change this
    Rises on a covered Ford with no 3-4 shift.

  3. Transmission computer software

    Supported by vehicle data
    Why it ranks here
    FCA reprograms the transmission computer on the 2015 Ram 1500 and Durango with P0734, and Kia addresses low-mileage shift issues on the 2014 Soul.
    What would change this
    Rises on a covered model that has not had the update.
    How to test the transmission control module (tcm)

  4. 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.

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 P0734 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 and speed sensor readings on a road test at cruising speed.

    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
  • No shift into fourth, or high engine speed at highway speed Gets more serious: stop and have it checked.
  • Overdrive off or transmission warning lamp flashing on some Fords
  • 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 P0734 bulletin or software update. Ford, FCA and Kia have issued them.

Parts and cost context

  • Transmission control module (TCM):Do not replace the module for P0734 unless a test points to it. The FCA and Kia fixes are software updates to the existing module.

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

Compare used part prices on PartPriceGuide

On your vehicle

Ford

  • 2008–2013 · F-150

    Supported by vehicle data

    Ford ASI-44538 ties P0734 or P0733 to direct clutch failure, with slipping in third or no fourth. On 2004 trucks built before 16 September 2003, 17305 covers the same code pair on the 4R75E. 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

  • 1999 · Taurus

    Supported by vehicle data

    Ford 9913140 links P0734 and no 3-4 shift to overdrive band wear on the AX4S. The Windstar is 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.

  • ASI-44538Status unverified

    Overdrive off lamp, slipping in third or no fourth, direct clutch failure

    2008–2013f-150, e-150, e-250, e-350, crown-victoria · issued · NHTSA 10056191

    Direct clutch failure with P0733 and/or P0734. Other Ford, Lincoln and Mercury models are also listed. 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.

  • 17305Status unverified

    4R75E transmission lamp with P0733 and/or P0734

    2004f-150 · 4.6L, 5.4L · issued · NHTSA 10004946

    4.6L and 5.4L trucks built before 16 September 2003. 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.

  • 9913140Status unverified

    AX4S P0734, flashing transmission lamp, no 3-4 shift or overdrive band wear

    1999taurus, windstar · issued · NHTSA 609053

    Some AX4S transaxles may show P0734, a flashing transmission lamp, no 3-4 shift or overdrive band wear. 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

  • 2015 · 1500

    Supported by vehicle data

    FCA 21-025-15 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.

  • 21-025-15Status unverified

    Transmission shift enhancements software update

    20151500 · issued · NHTSA 10150543

    Reprograms the transmission computer; P0734 is among the listed 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.

Dodge

  • 2015 · Durango

    Supported by vehicle data

    FCA 21-027-15 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.

  • 21-027-15Status unverified

    Transmission shift enhancements software update

    2015durango · issued · NHTSA 10150548

    Reprograms the transmission computer; P0734 is among the listed 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.

Kia

  • 2014 · Soul

    Supported by vehicle data

    Kia PS289 covers low-mileage shift issues with gear codes including P0734. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • PS289Status unverified

    Transmission shifting issues at low mileage

    2014soul · issued · NHTSA 10109717

    The MIL can come on with gear codes including P0734. 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: P0734. On cars with a separate transmission module, a basic code reader may show only P0700, which means the module has stored its own code. P0734 can be that code, so fix P0734 and P0700 goes with it.

  • P0733Transmission computer sees the wrong speed ratio in third gear

    Shares causes Supported by vehicle data

    Ford ties both codes to a failed direct clutch on some 2008–2013 models and to a 4R75E condition on 2004 F-150s.

  • P0731Transmission computer sees the wrong speed ratio in first gear

    Same system Possible — needs testing

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

  • P0732Transmission computer sees the wrong speed ratio in second gear

    Same system Possible — needs testing

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

All Transmission codes

P0734 questions

What does P0734 feel like?

Often the car will not shift into fourth, or the engine revs high at highway speed. Some cars show only the light.

Is it safe to drive with P0734?

Have it inspected soon. Toyota tells owners to get the car checked right away when the light is on for the transmission. If it starts slipping or will not shift, get it checked before relying on it.

Can a software update fix P0734?

On some models, yes. FCA and Kia have updates for P0734 on certain 2014–2015 vehicles, so ask a dealer to check your VIN.

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. Ford ASI-44538: Overdrive off lamp, slipping in 3rd or no 4th, direct clutch failure, P0733 / P0734 — Ford Motor Company / NHTSA ,
  4. Ford 17305: TCIL on with P0733 and/or P0734, 4R75E — Ford Motor Company / NHTSA ,
  5. Ford 9913140: AX4S P0734, flashing TCIL, no 3-4 shift or overdrive band wear — Ford Motor Company / NHTSA ,
  6. FCA 21-025-15: 845RE transmission shift enhancements, 2015 Ram 1500 — FCA US LLC / NHTSA ,
  7. FCA 21-027-15: Transmission shift enhancements, 2015 Durango — FCA US LLC / NHTSA ,
  8. Kia PS289: Transmission shifting issues at low mileage, 2014 Soul — Kia Motors America / NHTSA ,
  9. Tranny Problems: On the Outside Looking In — MOTOR Magazine ,
  10. Ford 19N01-S3: 6R80 molded leadframe extended coverage, 2011–2013 F-150 and 2012–2013 Expedition/Navigator — Ford Motor Company / NHTSA ,
  11. DTC P0700 — Saab 9-5 (9650) 2010 Workshop Information System — SaabWISOnline (community rehost of Saab/GM service information)
  12. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
Last reviewed
Written by
Saurabh K.
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