P0959 Diagnostic Trouble Code: Auto Shift Manual Mode Circuit Intermittent

Fault code P0959 is called “Auto Shift Manual Mode Circuit Intermittent” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0959

This diagnostic trouble code (DTC) is a generic transmission code. Error P0959 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.

P0959 Diagnostic Trouble Code: Auto Shift Manual Mode Circuit Intermittent

This code applies to vehicles equipped with a manual shift function on the automatic transmission. If you have this feature, you can manually control the gear shift by placing the shift lever in the notch next to the PRNDL marks.

If an intermittent signal is detected in the manual shift switch circuit on the automatic transmission. Then the code P0959 will be set and the manual shift function will be disabled.

Symptoms of vehicle malfunctions

The main signal that an error P0959 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The manual override function is disabled.
  2. There may be no symptoms other than a stored fault code.

The presence of diagnostic fault code P0959 will not significantly affect the vehicle’s handling and will not cause any internal damage. However, you will most likely not be able to shift gears manually.

Factors that can cause this error code

The error code P0959 can mean that one or more of the following problems have occurred:

  • Faulty manual shifter on automatic transmission.
  • Short-circuited or damaged wiring harness in gear shift circuit.
  • Faulty connection connector.
  • Sometimes the cause is a faulty PCM module.

How to fix or reset OBD-2 code P0959

Some suggested steps for troubleshooting and fix the error code P0959:

  1. Read all stored data and error codes with an OBD-II scan tool.
  2. Clear the error codes from the computer memory.
  3. Test-drive the vehicle to see if error P0959 appears again.
  4. Check the serviceability of the manual shift on the automatic transmission.
  5. Visually inspect the relevant wires and connectors for damage.
  6. If necessary, replace the defective parts.
  7. Test the PCM control module.

Diagnose and repair of problems

When diagnosing code P0959, it is worth checking the electrical part for damage. In today’s vehicles, electrical and electronic signals require good cabling for proper data transmission.

Any faults, such as breaks, disconnected connectors or corrosion, can interrupt signals, leading to transmission control failures. Next, check the battery, as some PCM and TCM modules are sensitive to low voltage.

If the battery is low, the system may detect this as a failure. Make sure the battery is delivering at least 12 volts and that the alternator is running properly, a minimum of 13 volts at idle.

The PCM control module fails very rarely, but it can happen. Therefore, when diagnosing error P0959, it should be checked if all other steps have already been completed.

On which vehicles does this problem occur most frequently

Fault code P0959 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Mercedes-Benz

Fault code P0959 can sometimes be found with other errors. The most common are the following: P0955, P0956, P0957, P0958.

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