P0783 OBD-II Trouble Code: 3-4 Shift Malfunction

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Cost of diagnosing the P0783 code

P0783 is a diagnostic trouble code (DTC) for "3-4 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.

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Check Engine Light

P0783 code definition

The P0783 code means that the PCM has detected an abnormal 3-4 shift function, which is necessary to decrease and increase speed, maximize engine performance, and optimize the vehicle’s fuel efficiency.

What the P0783 code means

The P0783 code indicates that there has been a malfunction in the third-to-fourth-gear shift. There are many factors that are used to measure the performance of gear ratios, including throttle position, engine loan, and vehicle and engine speed. Any of these could have delivered a calculation that indicated an improper gear ratio that does not coincide with the manufacturer’s designated reading stored in the PCM. On a practical level, this code means that the actual position of the gear is not the same as the position that it’s supposed to be in.

What causes the P0783 code?

Most of the time, the P0783 code is caused by a faulty shift solenoid. However, that is not the only possible cause. This abnormality may also be the result of:

  • Blocked transmission fluid passages
  • Internal transmission failures
  • Low transmission fluid
  • Dirty transmission fluid
  • Open or shorted shift solenoid valve harness
  • Poor electrical connection in the shift solenoid valve circuit
  • A faulty PCM or TCM (transmission control module), in rare cases

What are the symptoms of the P0783 code?

The symptoms of the P0783 code can vary dramatically. Some vehicle owners may only observe the illumination of the Check Engine lamp; however, others may experience serious symptoms such as:

  • Failure to shift into or out of a certain gear
  • Harsh shifting
  • Slipping transmission
  • Overheated transmission
  • Decreased fuel efficiency
  • Transmission controller in limp-in mode

Other shift solenoid codes may also be stored when the P0783 code is stored in the PCM.

How does a mechanic diagnose the P0783 code?

In order to diagnose the P0783 code, the mechanic will first use an OBD-II scanner to read the code in the PCM. If the code is detected, the first step to diagnosing a transmission issue is to visually inspect the transmission fluid dipstick. Low fluid should be filled, and dirty fluid should be drained to allow the mechanic to clean the system and refill it with clean transmission fluid. If the fluid doesn’t appear dirty, but smells burnt, there is a high possibility that clutch material or other debris is present, and a total flush will be needed.

After this repair is attempted, the mechanic should clear the code and retest the system. If the code returns to the PCM, then the next step is to inspect the electrical wiring, and begin repairing or replacing components as necessary until the solution is found.

Common mistakes when diagnosing the P0783 code

The most common misdiagnosis reported by technicians when faced with the P0783 code is to blame the shift solenoid itself, while electrical components in the shift solenoid circuit are actually to blame. It’s important to check the electrical components first, before replacing any parts, as these are frequently the problem.

How serious is the P0783 code?

The presence of the P0783 code represents a serious issue that should be repaired right away. The vehicle may become completely inoperable if left unattended.

What repairs can fix the P0783 code?

There are many ways that a technician can address a P0783 code detection. They include:

  • Replacing a faulty shift solenoid.
  • Flushing transmission fluid passages.
  • Refilling transmission fluid.
  • Repairing open or shorted shift solenoid valve harness.
  • Repairing poor electrical connections in the shift solenoid valve circuit.
  • Replacing a faulty PCM or TCM, in rare cases.

Additional comments for consideration regarding the P0783 code

It is always important to clear the code from the PCM and perform a retest after each repair is attempted. This action helps pinpoint what was the exact cause of the problem, which can make repairs faster in the future.

Need help with a P0783 code?

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.

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