Code P0756 means that the vehicle's PCM sensed an irregularity in shift solenoid B, which is located in the transmission. ... That's why the PCM pays attention to how shift solenoids are operating. These solenoids determine gear ratio based on engine load, throttle position, vehicle speed and engine speed.
How Serious is the Code?
A P0756 DTC is certainly not the end of the world, but it does mean that you will have to repair or replace your transmission in the near future.
Symptoms
Symptoms of a P0756 include:
- Check engine light
- Limp mode
- Harsh, delayed or erratic shifts
- Slipping in-and-out of gear
- Engine stalls
- Getting stuck in gear
- Vehicle won’t move when in gear
- Reduced fuel economy
- Transmission overheats
Causes
- Low transmission fluid
- Dirty transmission fluid / filter
- Frayed wiring / damaged connectors
- Failed solenoid
- Failed transmission pump
- Pressure blockage
- Valve body issue
- TCM or ECU failure
How to Diagnose the Code?
Many times, poor maintenance and dirty transmission fluid can lead to problems with the shift solenoids. To rule this out, a mechanic should first check the level and condition of the transmission fluid. If metal fragments are visible in the fluid, a rebuilt or remanufactured transmission may be required. If the fluid doesn’t appear to be “burnt”, then flushing the transmission may clear blocked internal passages.
Should no problems be found with the ATF, the wiring and connectors should be inspected for damage, corrosion and possible short circuits. If everything appears to be in good condition, then the solenoid will have to be tested according to the manufacturer’s recommended procedure. If no problems are found with the solenoid, then the transmission pump, valve body or pressure regulator could be suspected.
Common Mistakes When Diagnosing
It’s not uncommon to assume that the solenoid has failed, when in reality it was a wiring issue, or the solenoid wasn’t tested correctly. Dirty transmission fluid could also clog an internal passage, making it appear to be a failed shift solenoid.
What Repairs Will Fix P0756?
- Changing the transmission fluid and filter
- Replace faulty solenoid
- Repair or replace a faulty transmission pump
- Repair or replace defective transmission valve body
- Perform transmission flush to clean passages
- Cleaning corrosion from connectors
- Repairing or replacing wiring
- Flash or replace PCM/TCM
- Install a rebuilt or remanufactured transmission
Related Codes
P0755 – Shift Solenoid ‘B’
P0757 – Shift Solenoid ‘B’ Stuck On
P0758 – Shift Solenoid ‘B’ Electrical
P0759 – Shift Solenoid ‘B’ Intermittent
Hopefully this helps you.
