P1778Manufacturer-specific code

P1778 Code: CVT Step Motor Function (Nissan)

On Nissan and Infiniti vehicles, the P1778 code means the CVT step motor is not working as commanded. You may notice high engine speed with little forward motion. Other brands may define this number differently.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$200 to $3,500
Difficulty
Hard
System
Transmission
Applies to
Depends on the manufacturer

Common in: Nissan

Updated Reviewed by Renzo Chacca

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What the P1778 code means

P1778 is a manufacturer-specific code: the 1 in the second position means each automaker defines what it means, not the generic SAE standard. The most widespread definition is the one used by Nissan and Infiniti. If your vehicle is another brand, confirm the code text with a scan tool that supports that manufacturer.

ManufacturerMeaning of P1778
Nissan and InfinitiCVT step motor function

Nissan CVT transmissions change the ratio by moving the pulleys with a step motor. The transmission computer controls that motor and checks whether the actual ratio follows the command.

The computer sets the P1778 code when the step motor receives the command but the transmission ratio does not change the way it should: a mechanical failure of the motor, the pulleys or the pressure.

Before you start repairs, confirm the make, model, year and engine. With manufacturer codes, the same number can change even between engines from the same brand.

P1778 code symptoms

  • Poor acceleration.
  • High engine speed with little forward motion.
  • Limp mode.

Likely causes of the P1778 code

  1. Step motor jammed. Confirm it with the tests in the diagnosis section.
  2. Valve body. Check it by commanding it with the scan tool.
  3. Degraded CVT fluid. Check the level, condition and viscosity.
  4. Internal wear in the transmission. Confirm it with the tests in the diagnosis section.

How to diagnose the P1778 code step by step

  1. Check the CVT fluid.
  2. Watch the ratio on the scan tool.
  3. Look up the technical service bulletins.

How to fix the P1778 code

  • Change the CVT fluid with the original fluid.
  • Replace the valve body or repair the transmission.

Technical reference data

  • Use NS-2 or NS-3 fluid depending on the model.
  • P1xxx codes are manufacturer-specific: confirm the definition with a scan tool that supports your brand.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

CVT fluid is not interchangeable with regular ATF. Check that the right one is in the transmission before you assume the worst.

P1778 on Nissan

Common on the Sentra, Tiida, Versa, X-Trail and Altima with a CVT.

If your vehicle is another brand, check the table above for the meaning its manufacturer gives this code and confirm it with a compatible scan tool.

Frequently asked questions about P1778

What does the P1778 code mean on a Nissan?
It means the CVT step motor is not working as commanded. You may notice high engine speed with little forward motion.
Does P1778 mean the same thing on every brand?
No. It is a manufacturer-specific code, so on other brands it may not exist or may mean something different. Confirm it with a scan tool that supports your make.
Can I drive with a P1778 code?
With caution. Severity is high with a P1778 code, and the CVT can lose drive or go into limp mode, so get it checked soon.
How much does it cost to fix P1778?
Roughly $200 to $3,500 on a Nissan. A fluid change is at the low end, while a valve body or a transmission repair is at the top.
Will a P1778 code clear itself?
Not while the step motor or ratio problem is there. A fluid change may help in mild cases, but a mechanical fault brings the code back.
What is the most common cause of P1778?
A jammed step motor or a valve body problem. Degraded CVT fluid and internal wear come next.

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Questions about the P1778 code

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