What does it mean?
SPECIAL NOTES: Non-professional mechanics should note that code P0736 – “Reverse -incorrect ratio” is generally not repairable on a DIY basis. Diagnosing and repairing this code requires the use of advanced diagnostic equipment that may include specialized transmission simulators, as well as advanced knowledge of automatic transmissions in general and expert- level knowledge of the affected application in particular.
For these reasons, the information provided here is intended for general informational purposes only, and should NOT be used in ANY diagnostic procedure for this code on ANY application without making proper reference to the repair manual for the affected application. Even so, non-professional mechanics are limited to a few basic diagnostic steps that may or may not resolve the problem.
If the information provided here does not resolve the problem, do NOT attempt further repairs, but refer the vehicle to the dealer or a specialist transmission repairer for professional diagnosis and repair. END OF SPECIAL NOTES.
OBD II fault code P0736 is a generic code that is defined as “Reverse -incorrect ratio”, and is set when the PCM/TCM (Powertrain Control Module/Transmission Control Module) detects a problem while shifting into reverse gear, or while the vehicle is in motion with reverse gear selected. Note however that this code does not refer to a gear ratio as such, since most automotive applications have only one reverse gear ratio.
This code refers to a transmission’s inability to select reverse gear, a transmissions’ inability to maintain the reverse gear selection, or to a situation where the transmission’s actual speed does not agree with the transmission’s desired or expected speed while reverse gear is selected.
While the shift pattern in the forward gears are accomplished/managed by computer controlled shift solenoids, reverse gear is typically purely hydraulically operated in the sense that the reverse gear hydraulic circuit is either pressurized, or not. Moreover, the act of selecting reverse gear is not computer controlled- the driver has to select/deselect reverse gear manually via the gear selector.
Therefore, the diagnostic procedures that might resolve a shifting issue in a forward gear do not apply to reverse gear. Additionally, transmission design specifics and code setting parameters vary greatly between manufacturers which means, that in practice, the diagnostic and repair procedures for this code depend entirely on the specific transmission that is fitted to the application.
Nonetheless, when the PCM/TCM detects a problem with reverse gear selection, it will set code P0736, and illuminate a warning light.