P0766 OBD-II Trouble Code: Shift Solenoid D Performance or Stuck Off

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0766 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0766 code

P0766 is a diagnostic trouble code (DTC) for "Shift Solenoid D Performance or Stuck Off". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0766 DIAGNOSTIC Get a fair and transparent estimate upfront

Check Engine Light

P0766 code definition

The P0766 code indicates that there has been an abnormal voltage reading detected by the PCM in the shift solenoid D.

What the P0766 code means

Shift solenoids are used to managed the hydraulic fluid transfer between circuits, and to assist in the process that allows a vehicle to decelerate and accelerate. These solenoids must be able to actuate varying gear ratios to achieve vehicle speed and engine performance. If a solenoid (in this case, shift solenoid D) is not performing correctly, or is stuck in the off position, the engine will not perform at optimal level. In this case, the PCM will store the P0766 code.

What causes the P0766 code?

The most likely causes include:

  • Faulty shift solenoid
  • Blocked transmission fluid passages
  • Internal failures in the transmission
  • Low, dirty, or contaminated transmission fluid
  • Open or short shift solenoid D valve harness
  • Poor electrical connection within the solenoid D circuit
  • A faulty PCM or TCM, in very rare cases

What are the symptoms of the P0766 code?

In many cases, there are no symptoms at all beyond the illumination of the Check Engine lamp. However, some vehicle owners may observe:

  • Harsh shifting.
  • Transmission slippage.
  • Overheated transmission.
  • Decreased fuel economy.
  • Failure to shift into or out of a particular gear.

How does a mechanic diagnose the P0766 code?

After verifying the code with an OBD-II scanner, the mechanic should begin by inspecting the transmission fluid. If the fluid is too low, dirty, or smells burnt, it needs to be refilled or replaced with clean fluid. In the event that the transmission fluid is heavily contaminated, the entire system may need to be flushed and refilled.

The next step is to inspect all electrical components, and replace or repair any that are damaged, loose, corroded, or otherwise inoperable. After this step, a mechanic should check the hydraulic pressure, the shift solenoid function, and all related circuits until the improperly functioning component is found.

After every attempted repair is complete, the P0766 code should be cleared from the system, and a retest should be performed. If the code does not reappear, the mechanic has successfully diagnosed the issue, and will know precisely which component was causing the issue.

Common mistakes when diagnosing the P0766 code

The most common mistake made when diagnosing the P0766 code is jumping right to the shift solenoid itself, and replacing that component, rather than first checking the circuit components for electrical issues.

How serious is the P0766 code?

If the P0766 code is being detected, it indicates an issue that directly affects the operation of the vehicle. Even when symptoms are not present, this code means that the vehicle may not be operation for much longer, or that more expensive repairs will be needed down the road. If the P0766 code is detected, it should be dealt with immediately.

What repairs can fix the P0766 code?

There are many ways that a technician can address a P0766 code detection. They include:

  • Replacing faulty shift solenoid
  • Clearing blocked transmission fluid passages
  • Repairing internal failures in the transmission
  • Refilling low, dirty, or contaminated transmission fluid
  • Replacing open or short shift solenoid D valve harness
  • Repairing poor electrical connection within the solenoid D circuit
  • Replacing faulty PCM or TCM, in very rare cases

Need help with a P0766 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

trouble codes
Check Engine Light
P0766

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0766 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,936

Rating Summary
3,597
169
44
25
101
3,597
169
44
25
101

Noe

33 years of experience
545 reviews
Noe
33 years of experience
He defiantly knew what he was doing. He was here for just over a hour and did what needed to be done, explained everything to me and discussed what needed to be done in the future.
1995 FORD CROWN VICTORIA - CHECK ENGINE LIGHT IS ON - AUBURN, WASHINGTON

Clifton

27 years of experience
189 reviews
Clifton
27 years of experience
Great guy and very professional!
2009 AUDI TT QUATTRO - CHECK ENGINE LIGHT IS ON - BOCA RATON, FLORIDA

Dustin

10 years of experience
36 reviews
Dustin
10 years of experience
Service was great, however the manual for my vehicle may need to be reviewed and revised.
2008 GMC ENVOY - CHECK ENGINE LIGHT IS ON - GALENA PARK, TEXAS

Peter

40 years of experience
1059 reviews
Peter
40 years of experience
Peter was just great. He was very investigative and interested in solving the problem with my car. He was very thorough and detailed what the solution was to get my car back to running great.
1997 CADILLAC ELDORADO - CHECK ENGINE LIGHT IS ON - GLENDALE, ARIZONA

More related articles

P2422 OBD-II Trouble Code: Evaporative Emissions Control System (EVAP) Vent Valve Stuck Closed
Diagnostic Trouble Code (DTC): P2422 P2422 code definition Evaporative Emissions Control System (EVAP)...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...
P0684 OBD-II Trouble Code: Glow Plug Control Module to PCM Communication Circuit Range/Performance
P0684 code means there is a failing connection within the Glow Plug Control Module often due too corroded wires and solenoid failures.

Related questions

Q: Car cut off on the highway and never started back up.

Hello there, many faults will cause your 2004 Chevrolet Impala to die while running and not restart. The P0443 code is for the Evaporative Emission Control System Purge Control Valve Circuit and though this will need to be addressed will...

Q: My engine is surging at 2500 rpm's.

Hi there. First check the ECM for any codes that are present. If the codes are logged for the camshaft position sensor, then check harness to the camshaft position sensor and make sure that there is a reference voltage. If...

Q: Q: My car is shaking.

Hello. the Diagnostic Trouble Codes would have to be retrieved to begin the diagnosis. Unless the shop retrieved all codes and performed a diagnosis and tested the coils (there are six of them on your engine), what they have told...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com