Fix P0756: Mechanic’s solutions that WORKED

The code P0756: Shift Solenoid B Performance or Stuck Off points out a fault in the transmission’s shift solenoid B, indicating that it is either performing below expectations or stuck in the ‘off’ position. This solenoid is crucial for controlling the flow of hydraulic fluid in the transmission, which in turn manages gear shifts. When it fails or malfunctions, it can lead to issues with gear engagement, and shifting patterns, or even cause the vehicle to stay in a single gear.

P0756 quick overview

Meaning	P0756: Shift Solenoid B Performance or Stuck Off
Is it serious?	This code can be quite serious as it affects the transmission’s ability to shift gears properly, potentially leading to drivability issues.
Possible causes	– Faulty shift solenoid B – Hydraulic blockages inside the transmission valve body – Issues with transmission fluid (low level, dirty, or wrong type) – Malfunctioning transmission control module (TCM) – Wiring problems or poor electrical connections to the solenoid
How to diagnose?	Check Shift Solenoid: Verify the condition and operation of shift solenoid B. Inspect Transmission Fluid: Ensure the fluid is at the correct level, clean, and of the right type. Evaluate Electrical Connections: Look for damaged wiring or poor connections related to the solenoid. Examine Valve Body: Check for blockages or issues within the transmission valve body. Assess TCM Functionality: Verify that the transmission control module is functioning properly.

How to fix P0756 – learn from mechanics

I looked into P0756 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Isuzu

Vehicle Information: 2000 Isuzu Trooper S 3.5L

Issue + Repair History: Transmission problem with slipping in second gear. Found codes P0752 and P0756. Transmission rebuilt with new clutches, steels, gaskets, and torque converter. Still experiencing the same issue after rebuild.

Other OBD2 Codes + Test Results: P0752 P0756

Suggestions to Fix Issue:

• Check and possibly replace shift solenoid B.
• Look into potential issues with the Transmission Range Sensor, common in Isuzus.
• Replace valve body and solenoids.

Final Fix: The problem was resolved by removing and replacing the valve body.

Case #2: Oldsmobile

Vehicle Information: 1997 Oldsmobile Silhouette 3.4L Fwd & Od

Issue + Repair History:

• Came with code P0756.
• Previous shop replaced shift solenoid ‘B’.
• After erasing the code and test driving: starts in 2nd gear, shifts to 3rd, but no 1st and 4th gears.
• No slipping and no new codes after test drive.

Other OBD2 Codes + Test Results:

• P0756

Suggestions to Fix Issue:

• The issue was not specified in the discussion, but typically involves checking the transmission’s valve body, wiring, and related solenoids.

Final Fix:

• Replacing the 1-2 shift solenoid resolved the issue.

Case #3: Saturn

Vehicle Information: 2008 Saturn Outlook XR 3.6L Transmission

Issue + Repair History:

• Customer reported intermittent lack of drive and MIL on.
• Initial codes: P2723 (Pressure control solenoid 5 – stuck off) and P0756 (Shift solenoid 2 valve performance – stuck off).
• After initial test drive, no issue duplication, but P0756 returned post code clearing.
• Replaced broken 1 2 3 4 clutch wave plate, installed a rebuild kit, and replaced the TEHCM with a reconditioned one.
• Problem persisted: difficulty engaging gear, especially when cold, and P0756 reappeared.

Other OBD2 Codes + Test Results:

• P2723 – Cleared, did not return.
• P0756 – Cleared, but returned.

Suggestions to Fix Issue:

• Inquiry about whether the rebuild kit included solenoids.
• Recommendation to review a specific TSB for diagnostic tips on P0756.
• Suggestion to perform a fast adapt relearn procedure after replacing or programming internal parts or TCM.
• Clarification and understanding of TEHCM terminology.

Final Fix:

• Upon re-inspection and air checking the TEHCM and transmission, a faulty 1234 piston was identified and replaced. This resolved the issue.

Case #4: Honda

Vehicle Information: 2006 Honda Civic LX 1.8L Electronic

Issue + Repair History:

• Initially came in limp mode with code P0756 (solenoid B).
• Performed a fluid flush, cleared codes, and car shifted fine initially.
• Returned in 2 days in limp mode again with codes P0847 (pressure sensor B) and P0756 (solenoid B).

Other OBD2 Codes + Test Results:

• P0847: Pressure sensor B.
• P0756: Solenoid B.

Suggestions to Fix Issue:

• Check if the solenoid screen is clogged and clean or replace if necessary.
• Ensure wiring is intact with no damage and snug pin fits.
• Consider replacing the faulty solenoid, making sure to replace the correct one.
• Suggestion to change both the solenoid and pressure switch, ensuring the use of Honda-specific fluid.

Final Fix:

• Replaced the B solenoid and the external oil filter, resolving the issue.

Case #5: Ford

Vehicle Information: 2004 Ford F-250 Super Duty Harley-Davidson Edition 6.0L 1-2

Issue + Repair History:

• Transmission issues with shifting from 1-2 or 2-3, causing lock-up.
• Truck previously had transmission rebuilt and replaced.
• Codes P0756 and P0761 for B and C shift solenoid.
• Reverse sprag apparently damaged when transmission locks up.
• Electrical checks on solenoids and wiring showed no issues.

Other OBD2 Codes + Test Results:

• P0756: B shift solenoid.
• P0761: C shift solenoid.
• P2701, P2702.
• Solenoids ohmed at 5 ohms.

Suggestions to Fix Issue:

• Check for sticky valves in the valve body.
• Ensure all check balls are in the right places and in good condition.
• Verify if the manual valve in the valve body is the correct type.

Final Fix:

• Replaced transmission with a rebuilt unit, resolving the issue.

Advice for P0756	Brief Description of Diagnostic Step
Replace or Inspect Shift Solenoids	Check the functionality of the shift solenoids, especially Solenoid B, and replace if necessary.
Perform Transmission Fluid Flush	Flush and replace transmission fluid to ensure proper lubrication and functioning.
Check Wiring and Electrical Connections	Inspect wiring to the solenoids for damage or loose connections.
Inspect Valve Body	Examine the transmission’s valve body for sticky valves or misplaced check balls.
Consider Transmission Rebuild or Replacement	If solenoid replacement and other fixes fail, consider a more extensive transmission rebuild or replacement.
Ensure Use of Correct Parts and Specifications	Verify that all replaced parts, like solenoids, match the specific requirements of the vehicle.
Conduct Thorough Diagnostics Before Repair	Use diagnostic tools to accurately identify issues before deciding on a repair strategy.