P0766: Shift Solenoid D Performance/Stuck Off
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes with care - shift quality will suffer.
Symptoms
- Missing top gear
- Flaring on upshifts
- Poor fuel economy at speed
Likely causes, most common first
- Shift solenoid D stuck off
- Debris in the valve body
- Worn bore
- Low line pressure
Read P0766 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0766 is a performance fault on shift solenoid D - commanded but not delivering. Because solenoid D usually participates in the highest ratios, the common complaint is a car that will not reach top gear and runs at higher engine speed on the motorway.
Fluid condition tells most of the story here. Bright red fluid with a clean filter points at the solenoid or the bore; dark fluid with clutch material in the pan means the transmission has already been slipping and the solenoid is a symptom rather than the cause.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0766
“Vehicle jerks at low speed when accelerate and idle when accelerate, P0766 Code shows, engine noise and gears jump, when reverse the vehicle jerks.”2009 Mazda MAZDA6 · Sep 2024
Cars that report P0766 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0766?
Yes with care - shift quality will suffer.
How much does it cost to fix P0766?
Typical US repair costs range from $200 for the simplest fix (fluid and filter service) to $1,800 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0766. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.