P0766

Shift Solenoid D Performance or Stuck Off

Car Fault Codes Transmission

Severity High Get it checked soon and avoid long use.
Can you still drive? With care, short trips only
Who can fix it? Needs a specialist or dealer
Typical repair time 1 hour – 8 hours
Typical cost SAR 250 to 5,000

What it means

The transmission control module (TCM) has found that the gear ratio does not change as it should when shift solenoid D is commanded, so the clutch this solenoid feeds does not apply or slips. The cause is usually hydraulic, such as a clogged solenoid, low fluid or an internal leak.

Symptoms4

  • One or more gears missing, especially shifts that involve solenoid D.
  • Slipping and engine speed flare on some shifts.
  • Transmission entering limp mode.
  • Check engine light on.

Possible causes6

  • Low, old or burned transmission fluid.
  • Shift solenoid D clogged or stuck closed.
  • Clogged transmission filter or solenoid screen.
  • Worn valve or bore in the valve body.
  • Internal leak in the circuit of the clutch linked to solenoid D.
  • Worn clutch for the affected gear (less common).

How to diagnose5

  1. Check fluid level, color and smell.
  2. Identify the affected shift by comparing commanded and actual gear on a scan tool.
  3. Command solenoid D with the scan tool if possible and note the response.
  4. Inspect the pan and filter for metal particles or friction material.
  5. Have the removed solenoid bench tested or its hydraulic circuit pressure measured.

How to fix5

  1. Top up with the correct fluid, or change it and the filter.
  2. Replace shift solenoid D or the solenoid pack if it is proven to stick.
  3. Clean or replace the valve body if its valves are worn.
  4. Repair the internal leak or worn clutch if proven.
  5. Clear the codes, run the shift relearn if needed, then road test.

Repair cost

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

The cost is low when a fluid change or a new solenoid fixes it, and rises if a valve body or clutch repair is needed.

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

Should I start with the fluid or the solenoid?

Start with the fluid. If it is low or dirty, change it with the filter and retest; if the code returns, move on to the solenoid and valve body.

Could the fault be the clutch rather than the solenoid?

Yes. If the solenoid works and pressure is correct but slipping continues, the clutch or its seals are at fault, which requires opening the transmission.

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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