P0766 on Mazda
Shift Solenoid D Performance/Stuck Off
P0766 on Mazda vehicles indicates shift solenoid d performance/stuck off. Au7o has documented this code across 1 Mazda model — most commonly on Mazda3. This code means the Transmission/Powertrain Control Module detected that Shift Solenoid 'D' is performing poorly or appears stuck in the off position. Shift solenoids direct hydraulic fluid inside the transmission to engage the proper gears or apply the torque converter clutch, and the module monitors whether commanded shifts actually occur. P0766 sets when solenoid D isn't producing the expected result — the gear change tied to it doesn't happen correctly. This can cause harsh or missed shifts, slipping, or being stuck in a gear, sometimes triggering limp mode. Typical repair costs on Mazda range from $400 to $2,500, depending on the specific model and root cause.
Common Causes of P0766
- •Stuck or failed shift solenoid D
- •Low or contaminated transmission fluid
- •Clogged solenoid screen or valve body passage
- •Open, shorted, or corroded solenoid wiring/connector
- •Valve body wear or sticking spool valve
- •Internal hydraulic leak affecting the solenoid circuit
- •Faulty TCM/PCM solenoid driver
P0766 on Mazda by Model
Mazda Mazda3(1 issue)
- 2004-2009 Mazda3 FN4A-EL Four-Speed Automatic Shift Solenoid and Valve Body Faults2004-2009
The FN4A-EL (Mazda's version of the Ford 4F27E) four-speed automatic used in the BK Mazda3 suffers sticking shift solenoids and worn valve-body bores. When a solenoid sticks or its driver circuit in the TCM fails, line pressure is no longer properly controlled: the car bangs into gear, flares between shifts, holds a single gear in limp mode, or refuses to shift out of first. Owners report the P0766/P0767 (shift solenoid D) and P0771 (shift solenoid E) family of codes, frequently after the fluid has gone past its life and clutch debris has circulated through the valve body. Long-neglected fluid accelerates it - the burnt clutch material is what makes the solenoid valves stick in the first place.
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What does P0766 mean on Mazda?▼
P0766 stands for "Shift Solenoid D Performance/Stuck Off." This code means the Transmission/Powertrain Control Module detected that Shift Solenoid 'D' is performing poorly or appears stuck in the off position. Shift solenoids direct hydraulic fluid inside the transmission to engage the proper gears or apply the torque converter clutch, and the module monitors whether commanded shifts actually occur. P0766 sets when solenoid D isn't producing the expected result — the gear change tied to it doesn't happen correctly. This can cause harsh or missed shifts, slipping, or being stuck in a gear, sometimes triggering limp mode. On Mazda specifically, this code is documented across 1 model.
What causes P0766 on Mazda vehicles?▼
Common causes on Mazda: Stuck or failed shift solenoid D, Low or contaminated transmission fluid, Clogged solenoid screen or valve body passage, Open, shorted, or corroded solenoid wiring/connector, Valve body wear or sticking spool valve. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0766 on a Mazda?▼
Repair costs on Mazda range from $400 to $2,500, depending on the specific model and root cause.
Which Mazda models have P0766 documented?▼
Au7o has documented P0766 on 1 Mazda model: Mazda3.