P0755 OBD-II Trouble Code: Shift Solenoid B Malfunction

Check Engine Light

P0755 code definition

The P0755 code indicates that the transmission’s shift solenoid B has experienced a malfunction, and the computer has detected it.

What the P0755 code means

The P0755 code indicates that there is a problem with the transmission’s shift solenoid B. Note that this only applies to automatic transmissions. Your transmission has multiple shift solenoids that are used to manage fluid transfer and flow from one circuit to another in order to shift gears. If the P0755 code is set, it means that the computer has detected that the actual gear ratio used is different from the gear ratio calculations based on input from engine speed, throttle position and other aspects. Note that some vehicles may require more than one erroneous operation for the code to be stored.

What causes the P0755 code?

A number of potential causes are possible with the P0755 code. These may include:

  • Low transmission fluid indicating a leak
  • An internal blockage preventing fluid from flowing correctly
  • A faulty shift solenoid
  • Internal mechanical failure in the transmission
  • Contaminated transmission fluid
  • A failed PCM or TCM (not common)

What are the symptoms of the P0755 code?

If the P0755 code is stored in your car’s computer, you could experience a wide range of symptoms. These vary depending on the severity of the situation, as well as the make and model in question. They can include:

  • The Check Engine Light on
  • Failure to shift into gear
  • Failure to shift out of gear
  • Transmission slipping
  • Harsh shifting
  • Transmission overheating
  • Reduced fuel efficiency
  • The transmission being locked into “limp-home” mode

How does a mechanic diagnose the P0755 code?

The first step in diagnosing the cause of the P0755 code is to check the level and condition of the transmission fluid. If the fluid is low, it must be topped off before taking any further steps. If the fluid is dirty or contaminated, it will need to be changed before taking any other steps. Note that if the fluid smells burned or contains shavings, the mechanic will need to check the rest of the fluid in the drain pan. Metal shavings indicate internal damage to the transmission, and possibly the need for a rebuild.

Next, the mechanic will connect the car to an OBD II scanner to read the code and any other stored information. The codes will then be cleared and the vehicle test driven to see if the code resets. If it does, the mechanic will then check the shift solenoid, its wiring harness, connections and the shift solenoid circuit itself.

Common mistakes when diagnosing the P0755 code

The most common mistake here is replacing the shift solenoid, when the problem actually lies with the shift solenoid circuit. This leads to incorrect repairs and increased frustration for the owner. Other mistakes include not checking the transmission fluid level and condition prior to replacing the shift solenoid.

How serious is the P0755 code?

The P0755 code is very serious. While it might not result in immediate driving problems, it is a sign that there is something wrong with your transmission. It is essential to have it diagnosed and repaired before further damage is done.

What repairs can fix the P0755 code?

The most common repair for the P0755 code is replacement of the shift solenoid circuit. However, other repairs may include:

Additional comments for consideration regarding the P0755 code

It is important that mechanics take all appropriate diagnostic steps when dealing with a P0755 code. Assuming that the code indicates the shift solenoid itself is at fault is the wrong way to proceed. There are many potential causes, and they must all be ruled out.

Need help with a P0755 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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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