P0759 code definition
The P0759 code means that the powertrain control module (PCM) has detected that there is an irregularity in shift solenoid A. Other shift solenoid codes may accompany this code, such as P0754.
What the P0759 code means
The OBD-II generic code for a problem in vehicles with automatic transmissions, the P0759 code means that the shift solenoid B may not be properly managing fluid levels between its hydraulic circuits. This may be preventing the vehicle's transition from adjusting properly, which can cause problems in acceleration or deceleration, fuel efficiency and engine performance.
What causes the P0759 code?
- A PCM or transmission control module failure or fault
- Contaminated or dirty transmission fluid
- Defective shift solenoid
- Hydraulic blockages within the transmission fluid canals
- Low transmission fluid
- Mechanical failures within the transmission
What are the symptoms of the P0759 code?
The P0759 may have no symptoms, but may also cause the transmission to slip, to shift heavily, and to overheat. The vehicle's transmission controller may also move into "limp in" mode in order to prevent the engine from being damaged.
How does a mechanic diagnose the P0759 code?
A P0759 code will be diagnosed with the OBD-II scanner. It is advisable that the freeze frame data is used to recognize when the code appeared, noting any codes relating to transmission and temperature that may have appeared prior to it. The mechanic will then reset the codes and do a road test to determine if the code returns. If so, the next step is to check the transmission, beginning with fluid levels and conditions.
Look for indications of burnt fluid, and if there are odors and burnt fluid, it is important to drop the transmission pan and look for debris, as this means a rebuild is required. If there is no debris, it is likely that the problem is due to a fault in the system's wiring and connections, and the full internal transmission harness may need to be replaced before another diagnostic is run.
Common mistakes when diagnosing the P0759 code
It is not unusual for mechanics to mistakenly identify the shift solenoid as the problem, replacing it and yet seeing the code return. This is because the issue is more often the shift solenoid circuitry and not the solenoid itself.
How serious is the P0759 code?
A P0759 code does prevent the car from operating, but it can come with dangerous symptoms, including overheating, engine problems, and issues with vehicle control. If serious enough, it can lead to costly transmission rebuilds.
What repairs can fix the P0759 code?
The P0759 code is dealt with using these repairs:
- The mechanic must run full diagnostics with a code reader or scanner. They will reset the codes and then perform a road test to determine if the P0759 code resets or returns.
- When it does, a technician or mechanic must start with a transmission diagnosis. This means checking the fluid levels and gauging the conditions as well as amounts of fluid.
- If there are signs of burnt transmission fluid, it is necessary to drop the transmission pan and look for clutch debris. When this is found, the transmission must be rebuilt, the fluid flushed and a new torque converter installed.
- If there is no debris, it is most likely a problem in the solenoid circuitry and most mechanics will do a full internal transmission harness replacement. They should also inspect all of the wiring, replacing and repairing as needed.
Additional comments for consideration regarding the P0759 code
If the diagnostics and inspections fail to yield results, and the code still appears, it can be that the vehicle is in need of a new pump. This can be determined through the use of a manual pressure gauge, with the readings compared to the vehicle manufacturer's suggested specifications.
Need help with a P0759 code?
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