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Diagnostic is a diagnostic trouble code (DTC) for "Trouble Code (DTC) P0780 Shift Malfunction". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $79.99. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0780 code means that that car’s computer has detected a malfunction with the transmission shifting.
The P0780 code means that there has been an abnormality with the transmission shifting. Note that this code only applies to automatic transmissions. This code is also often associated with other, similar codes, such as P0755 Shift Solenoid B Malfunction. Automatic transmissions use shift solenoids to move fluid through internal circuits and channels to create pressure differences, thus shifting gears. If fluid does not move as expected, and there is a variance between the actual gear ratio and the gear ratio expected based on engine inputs (throttle position, engine speed, etc.), then the computer will set the P0780 code.
There are many potential causes of the P0780 code, and they are similar to the causes of the P0755 code. They include the following:
Symptoms of the P0780 code can range dramatically, depending on the make and model in question, as well as the actual underlying cause. They include the following:
As with most other DTC codes, the P0780 code will first need to be diagnosed by connecting an OBD II scanner to the car’s communications port. This is located on the driver side under the dash, usually. The technician will read the code (or codes) and then clear the system. A test drive will be needed to make sure the code resets.
The next step will be to check the level of transmission fluid (low fluid is one of the most common causes). If the transmission fluid is low, it will need to be topped off, the code cleared and the car test driven again. Sometimes, this is all that is needed. If the transmission fluid is dirty, it will need to be drained and refilled (possibly with a filter replacement). If the transmission fluid smells burned or contains finings, the pan will need to be removed and the technician will inspect for signs of damage. In this instance, a transmission rebuild may be necessary.
If the fluid level and condition are good, the mechanic will then inspect the shift solenoids, as well as their wiring harnesses. While failed solenoids may cause the code, it is also possible that there is damage to the harness, or corroded wiring connections. The technician will also check the pump’s pressure using a manual gauge to ensure that pressure readings are in line with manufacturer specifications. If they are not, the pump may be clogged or failing.
The most common mistake is replacing shift solenoids without conducting a full, thorough inspection. Often, the underlying problem is related to transmission fluid level or condition. It may also be related to a faulty shift solenoid circuit, rather than the solenoid itself.
The P0780 code is serious, even if you’re not experiencing drivability problems yet. It can lead to serious transmission damage, causing expensive repairs.
There are several potential fixes for the P0780 code, depending on the underlying cause. They include the following:
Regular transmission maintenance can help prevent the P0780 code by keeping your transmission fluid clean and at the correct level.
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.