Guide To P0757 OBD Error Code Solutions

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P0757 OBD-II trouble code is associated with a detected stuck on transmission Shift Solenoid "B". Due to this trouble code you might start facing problems like overheating of transmission, slippage of transmission, problem in shifting into gears etc. This trouble code should be corrected in timely manner else can progress into a more severe level. Trouble code P0757 indicates that PCM has registered an irregularity with shift solenoid B.

P0757 is a diagnostic trouble code (DTC) for "Shift Solenoid B Stuck On". The P0757 code is detected when the ECM has detected a mechanical fault with the solenoid energized, valve stuck on. Shift solenoid valve B is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position. If the desired gear ratio fails to coincide with the actual gear ratio detected, a code will be stored and a malfunction indicator lamp may be illuminated.

What causes this problem with the Shift Solenoid B Stuck On?

• Defective shift solenoid B valve
• Low transmission fluid level
• Dirty transmission fluid
• Open or shorted shift solenoid B valve circuit
• Poor electrical connections
• Choked transmission filter
• Faulty PCM

1. Shift Solenoid - A shift solenoid opens and closes the valves that allow hydraulic fluid to flow in and out of a transmission. It is computer-controlled and electronically activated. A faulty shift solenoid can prevent fluid pressure from activating the appropriate gear. As a result, the transmission may not shift gears or it may get stuck in neutral. Ensure its proper functioning and if you discover it faulty replace it.
2. Shift Valves - The shift valves are simple balance- type spool valves that select between low and high gear when the manual valve is in drive. Using control pressure, they operate the bands, servos, and gear sets. Faulty shift valves can also be the reason causing this error code.
3. Transmission Filter - Transmission filters help prolong the life of your transmission by filtering out debris. It doesn’t let your transmission fluid to be contaminated and your vehicle can continue to drive at its optimal potential. It should be replaced immediately if found clogged.
4. Transmission Valve Body - The valve body is the control center of the automatic transmission. It contains a maze of channels and passages that direct hydraulic fluid to the numerous valves which then activate the appropriate clutch pack or band servo to smoothly shift to the appropriate gear for each driving situation. If it is faulty then create drivability issues.
5. Powertrain Control Module - The PCM or Powertrain Control Module of your car is a critical automotive component or rather a combined control unit. Like human brain, which controls and coordinates the different functions and activities of human body, PCM acts as the brain of your car, and it controls and coordinates the functions of the different subsystems of your car. Repair or replace the faulty components of PCM to ensure the smooth functioning of your vehicle.

Following are some common symptoms associated with this trouble code P0757:

• Transmission will not shift gears
• Overheated transmission
• Slippage of transmission
• Vehicle may enter into limp mode
• Reduced fuel economy
• Illuminated check engine light

Due to this trouble code P0757, the main problem that occurs will be problem in shifting gears and if you continue to drive your vehicle ignoring this error code, you might end up doing plenty of damage to your vehicle. This error code should not be ignored and looked up at earliest. To fix this code following repairs or replacements may help:

• Changing the transmission fluid and filter
• Repair or replace a faulty shift solenoid
• Repair or replace defective transmission valve body
• Repair or replace defective transmission
• Cleaning corrosion from connectors
• Repairing or replacing wiring

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It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P0757 code to be stored:

• Begin any transmission diagnosis with an inspection of the transmission fluid dipstick (if equipped).
• Make sure that the fluid level is within manufacturer’s specified recommendations and that the fluid is in good condition.
• Visually inspect all internal wiring and connectors, look for shorted or burned wiring and replace circuitry and connectors as required.
• If the system wiring, connectors, and components appear to be in normal working order, connect the scanner to the diagnostic connector and record all stored trouble codes and freeze frame data.
• If the transmission fluid appears to be in decent shape, but the fluid level is low, add enough fluid to locate a leak and repair it.
• If either the reference voltage or ground circuits are open, use the digital volt/ohmmeter to check for continuity (disconnect all related control modules from the circuit before checking circuit resistance or controller damage may occur) and resistance in all circuits.
• Repair or replace system circuitry, connectors, and/or components that fail to coincide with manufacturer’s specs.
• Always retest the system to ensure a successful repair. If all system circuits are intact connecting the scanner to the diagnostic connector and attempt to manually activate the shift solenoid/s in question.
• If the shift solenoid functions properly and all circuits coincide with manufacturer’s specifications, suspect a defective PCM.
• Remember that PCM failure is rare and replacement will require reprogramming.

Common Mistakes When Diagnosing the P0757 Code

Most commonly, mechanics will replace shift solenoid B without conducting a full diagnosis. While a failed solenoid is often the culprit, there are other factors that must be ruled out. Often, low transmission fluid is the problem.