What does it mean?
Modern vehicles equipped with automatic transmissions/transaxles use a torque converter between the engine and transmission to increase engine torque and drive the rear wheels.
This code may appear in vehicles with automatic transmissions when there is a problem shifting into reverse or while in reverse. The automatic transmission changes the output direction to move the vehicle in reverse and is most often manually controlled by hydraulic pressure, even in computer-controlled transmissions.
The Engine Control Module (ECM), Powertrain Control Module (PCM), or Transmission Control Module (TCM) uses inputs from various sensors to verify the proper operation of the transmission and its components. Engine speed is often calculated relative to the transmission speed sensor to determine the gear ratio and torque converter slip. If the calculation does not match the desired value, a diagnostic code is set and the Check Engine light is illuminated. Incorrect ratio codes typically require advanced mechanical skills and diagnostic tools.
Note: This code is similar to P0730, P0730, P0731, P0732, P0733, P0734, and P0735. If there are other transmission codes, repair those issues before proceeding with an incorrect gear ratio code.
Symptoms
Symptoms of a P0736 trouble code may include:
Check Engine light illuminated (malfunction indicator)
Delayed or no shift into reverse
Transmission slipping
Potential Causes
Causes
of this DTC may include:
Low or dirty transmission fluid
Mechanical failure inside the transmission
Internal blockage within the transmission main control
Faulty shift solenoid
Faulty transmission control module
Diagnostic
/ repair steps
Always ensure to check the fluid level and condition before proceeding with diagnosis. Incorrect fluid level or dirty fluid can cause shifting problems affecting multiple gears. If only one incorrect ratio code is displayed, test the vehicle to determine if the gear is actually functioning.
Transmission internal clutches and bands are typically controlled by a solenoid or using fluid pressure. If there is an electrical issue with a shift solenoid, a code specific to that fault should also be displayed. Fix the electrical issue before proceeding. Blocked fluid passages inside the transmission can also prevent the vehicle from shifting into reverse; if there are multiple incorrect ratio codes but the transmission operates as expected, there might be a mechanical issue with the torque converter, transmission main control, or pressure problems.
If there are multiple incorrect ratio codes and shifting issues, but not all are displayed, the fault could be an internal mechanical problem within the transmission, or fluid pressure/blocked passages in the main control. A shift solenoid controlling multiple gears could also be at fault in case of internal blockage or fluid pressure issues. If there is an electrical issue with the solenoid controlling the gears, a code should be displayed specific to the faulty solenoid.
Reverse gear in the transmission is generally not controlled by a solenoid; it is entirely hydraulic. If the transmission does not shift into reverse, there is most likely a mechanical or pressure issue causing the problem.
It may be necessary to use an advanced diagnostic scan tool to determine which gear is commanded by the transmission and to verify if the engine speed matches the calculated output speed from the transmission sensor.
In-depth knowledge of transmission operation and overhaul is often required to repair this type of malfunction. Consult the factory service manual for vehicle-specific diagnostic procedures.