P1778

CVT Step Motor Function

Car Fault Codes Nissan Transmission

Can you still drive? With care, short trips only

Who can fix it? Needs a specialist or dealer

Typical repair time 1 hour – 16 hours

Typical cost SAR 300 to 12,000

What it means

This is a Nissan-specific code for vehicles with a CVT; the same number can mean something different on other makes. It means the transmission control module (TCM) commanded the step motor to change the ratio, but the actual ratio calculated from the pulley speed sensors did not change as expected. The electrical circuit may be fine; the problem is usually mechanical or hydraulic inside the transmission.

Models covered: Nissan models with CVT, mainly around 2003–2012 (e.g. Murano, Altima, Sentra, Tiida/Versa, X-Trail).

Symptoms4

Weak acceleration or a slipping feel with high engine speed.
The ratio does not change smoothly, or stays at a low or high ratio.
The transmission enters fail-safe mode.
Check engine light on, and a whine or unusual noise from the transmission may be heard.

Possible causes5

Low, aged or wrong-type CVT fluid.
A mechanically sticking or weak step motor.
A dirty or worn control valve assembly restricting ratio changes.
Wrong readings from the primary or secondary pulley speed sensor.
Internal wear of the pulleys or steel belt, the most costly cause.

How to diagnose5

Read all codes; P1777 means start with the electrical circuit, while fluid pressure or speed sensor codes guide the diagnosis.
Check CVT fluid level, condition, color and smell per the Nissan procedure.
Watch commanded step motor steps against the actual ratio on a Nissan-capable scan tool while driving.
Check both pulley speed sensors and their readings.
Inspect the fluid pan and strainer for metal debris that indicates internal wear.

How to fix5

Correct the fluid level, or replace aged fluid with the CVT fluid type specified by Nissan.
Repair or replace a faulty speed sensor.
Replace the step motor or control valve assembly, then write calibration data to the TCM if the model requires it.
Replace or rebuild the transmission if pulley or belt wear is confirmed.
Clear the codes and road test in varied conditions.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when a fluid change or sensor repair is enough, rises with a step motor or valve assembly, and is highest when the transmission must be replaced or rebuilt.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

What is the difference between P1777 and P1778?

P1777 is an electrical fault in the step motor circuit. P1778 means the circuit works but the actual ratio does not follow the command, which points to a mechanical or fluid cause.

Is a CVT fluid change enough?

Sometimes, if the fluid is low or aged, as long as the type specified by Nissan is used. If the code returns, the step motor, valve body or internal wear is more likely.

Should I keep driving?

Drive as little as possible and avoid hard acceleration, because slipping inside a CVT can speed up belt and pulley wear and raise the repair cost.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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