P1778 Manufacturer-specific code. On Nissan CVTs: step motor function, the actual pulley ratio not following the step motor command

Nissan CVT step motor function

P1778 in short

P1778 is a Nissan CVT code meaning the actual pulley ratio is not following the step motor command. Nissan fixed many 2010 models by replacing the valve body and reprogramming the computer, and a CVT specialist says the step motor itself is often replaced for nothing. Have it inspected soon.

In Nissan's JATCO CVTs, a step motor moves a valve that sets the pulley ratio. The CVT computer commands a step motor position and checks that the actual ratio follows. P1778 sets when the two do not agree.

Nissan issued bulletins for 2010 Altima, Rogue, Sentra, Murano and Maxima models with slower than normal acceleration from a stop and P1778. On the Altima, Rogue and Sentra the fix is a new control valve (valve body) and a computer reprogram.

Gears magazine warns that step motors are often replaced needlessly for this code. It points instead to valve body wear, pulley leaks and worn flow control valves, so a shop should test before buying a step motor.

Pick your make

P1778 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Control valve (valve body) and computer programming (2010 Nissan)

    Supported by vehicle data
    Why it ranks here
    Nissan replaces the control valve and reprograms the CVT computer for P1778 with slow acceleration on 2010 Altima, Rogue and Sentra.
    What would change this
    Rises on a covered 2010 model with slow acceleration from a stop.
    How to test the transmission control module (tcm)

  2. Valve body wear, pulley leaks or worn flow control valves

    Possible — needs testing
    Why it ranks here
    A CVT specialist reports these as the usual causes of P1778 rather than the step motor.
    What would change this
    Rises on a high-mileage CVT or if the fluid is dark.

  3. Step motor fault

    Possible — needs testing
    Why it ranks here
    The step motor is the part being checked, but a CVT specialist says it is often replaced without fixing the code.
    What would change this
    Rises only if a shop has ruled out the valve body and leaks.

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.

    Low riskTool: scan tool that reads the transmission module

  2. Ask a Nissan dealer, or check the NHTSA site, for P1778 bulletins on your VIN.

    Low risk

  3. Have a CVT shop compare commanded and actual ratio and check for valve body wear and pulley leaks before replacing the step motor.

    Best left to a shopTool: scan tool with CVT data

    Warning:Shop test. Nissan CVTs need the maker's fluid check procedure and fluid, and the step motor is inside the transmission.

Symptoms

  • Check engine light
  • Slower than normal acceleration from a stop
  • CVT in fail-safe mode with reduced power Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

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

  2. Ask a Nissan dealer whether a P1778 bulletin applies to your VIN, especially on 2010 models.

  3. Do not buy a step motor on the code alone. A CVT specialist reports it is often replaced without fixing the problem.

Parts and cost context

  • Transmission control module (TCM):Nissan's fix on 2010 models pairs a new valve body with a computer reprogram, not a new computer.

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

Compare used part prices on PartPriceGuide

On your vehicle

Nissan

  • 2010 · Altima

    Supported by vehicle data

    Nissan NTB10-150A and NTB11-002C cover slow acceleration from a stop and P1778. The repair is a new control valve and a computer reprogram. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

    Where it is:Control valve inside the CVT

  • 2010 · Rogue

    Supported by vehicle data

    Nissan NTB10-150A covers slow acceleration from a stop and P1778, with a new control valve and a computer reprogram. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

    Where it is:Control valve inside the CVT

  • 2010 · Sentra

    Supported by vehicle data

    Nissan NTB10-150A covers slow acceleration from a stop and P1778, and P0720 on Sentras without ABS. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

    Where it is:Control valve inside the CVT

  • 2010 · Murano

    Supported by vehicle data

    Nissan NTB11-002C covers slow acceleration from a stop and P1778. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

  • NTB10-150AStatus unverified

    Slower acceleration from a stop, P1778 and/or P0720

    2010altima, rogue, sentra · issued · NHTSA 10192259

    Covers slower than normal acceleration from a stop and/or the MIL with P1778, or P0720 on Sentras without ABS. Replace the control valve and reprogram the CVT computer. 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.

  • NTB11-002CStatus unverified

    Slower acceleration from a stop, P1778

    2010murano, altima, maxima · issued · NHTSA 10192260

    Covers slower than normal acceleration from a stop and/or the MIL with P1778. Follow the repair flow chart. 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: P1778. On cars with a separate transmission module, a basic code reader may show only P0700, which means the module has stored its own code. P1778 can be that code, so fix P1778 and P0700 goes with it.

  • P0720Transmission output shaft speed sensor circuit fault

    Shares causes Supported by vehicle data

    Nissan covers P1778 and, on the 2010 Sentra without ABS, P0720 in the same bulletin.

All Transmission codes

P1778 questions

Should I replace the step motor for P1778?

Not on the code alone. Nissan's 2010 fix was a new valve body and a reprogram, and a CVT specialist says step motors are often replaced without curing the code.

Sources and review

  1. 2020 Nissan Altima Owner's Manual — Nissan North America
  2. Nissan NTB10-150 / NTB10-150A: slower acceleration from a stop, P1778 and/or P0720 — Nissan North America / NHTSA ,
  3. Nissan NTB11-002C: slower acceleration from a stop, P1778 — Nissan North America / NHTSA ,
  4. Cal. Code Regs. Tit. 13, § 1968.2 — Malfunction and Diagnostic System Requirements (OBD II) — California Air Resources Board (via Cornell LII)
  5. Stop Wasting Money on JATCO CVT Stepper Motors — GEARS Magazine (ATRA)
  6. DTC P0700 — Saab 9-5 (9650) 2010 Workshop Information System — SaabWISOnline (community rehost of Saab/GM service information)
Last reviewed
Written by
Saurabh K.
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