P0766 code meaning
Shift Solenoid D Performance/Stuck Off
Powertrain system Generic code P07xx codes Check engine light
What P0766 means
A shift solenoid is an electrically switched valve in the valve body; the module checks whether its clutch follows the command by gear ratio, shift time or a pressure switch. P0766 means solenoid D is commanded on but its clutch does not follow. Ford checks gear ratio over 10 events (2012) or 3 (2020–23 and the 2023 diesel); on the 6F transmissions solenoid D feeds two clutches, so Ford recognises a solenoid fault when both fail, while a single clutch fault sets ratio codes. Ford's 10R80 bulletins list it with a leaking clutch cylinder; Dodge's Aisin AS6 uses it for solenoid 4. GM does not use P0766.
P0766 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1.5 to 12 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0766
- Upper gears (4th–6th) missing, or no reverse or engine braking in first (Ford)
- Slip or engine flare on shifts
- Limp mode
- Check engine light
Common causes of P0766
- Most likelyClutch or brake of this circuit leaking or worn (piston seal, linings)
- PossibleShift spool or proportional valve sticking (dirt, debris)
- PossibleFluid level or quality
- Less likelyPressure switch faulty (Allison, Aisin)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Shift solenoidTransmission valve bodyTransmission wiringTransmission control module
What each part of P0766 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 66 | The exact fault in that area. |
What to do next
- Note P0766 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0766
What does P0766 mean?
P0766 means "Shift Solenoid D Performance/Stuck Off". A shift solenoid is an electrically switched valve in the valve body; the module checks whether its clutch follows the command by gear ratio, shift time or a pressure switch. It is a generic code, so it means the same on every make.
Is it safe to drive with P0766?
Drive gently and only to a workshop. With P0766 the car can go into limp mode (reduced power) to protect itself.
Will P0766 fail an emissions test?
Yes, it can. P0766 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0766 to fix?
Difficulty: hard. A typical repair takes 1.5 to 12 hours of work. This is a job for a workshop.
Will P0766 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.