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P0973 OBD-II Trouble Code: Shift Solenoid A Control Circuit Low

Check Engine Light

P0973 code definition

The P0973 trouble code detects an error with the shift solenoid A control circuit

What the P0973 code means

The P0973 code is a generic trouble code that notes a problem with the shift solenoid valve A. The shift solenoids are controlled by the transmission control module (TCM), and are activated and deactivated to alter gear ratios and allow for smooth shifting in the automatic transmission. Depending on the make and model of the vehicle, the valve A shift solenoid may control the clutches, brakes, or bands in the transmission. When the TCM notes that the readings from the shift solenoid are abnormal, the control circuit will be shut down, and the powertrain control module (PCM) will store the P0973 trouble code.

What causes the P0973 code?

The P0973 trouble code can be caused by a few different things:

  • Defective shift solenoid valve A
  • Damaged wires or connectors in the system
  • Defective control circuit
  • Low or dirty transmission fluid
  • In rare cases, a malfunctioning TCM, PCM, or engine control module (ECM)

What are the symptoms of the P0973 code?

When the P0973 code is detected, the vehicle’s check Engine Light will likely illuminate on the dashboard. It is probable that the vehicle will experience difficulty or an inability to shift into certain gears, which can cause drivability issues such as harsh shifting and uneven acceleration. It is also common for the fuel efficiency to be diminished.

How does a mechanic diagnose the P0973 code?

The P0973 code will be addressed using a standard OBD-II trouble code scanner. A reputable technician will look at the freeze frame data to assess the code and check for the existence of additional codes. If multiple trouble codes are detected, they should be inspected in the order in which they appear on the scanner. The trouble codes will then be reset and the vehicle restarted, so that the mechanic can see if the code remains detected. If the code disappears, it was most likely the result of an intermittent error, or possibly an erroneous detection.

If the code remains, then the mechanic will need to visually inspect the electrical components in the transmission. Wires and connectors should be checked to see if they are shorted, open, or damaged, and replaced as necessary. The transmission fluid will then be checked, with low fluid being refilled, and dirty fluid being replaced. If the transmission fluid is extremely contaminated, then there is likely a more severe issue with the transmission, and it will probably require a rebuild or replacement.

A digital volt/ohmmeter can then be used to identify which circuit corresponds with the valve A shift solenoid, and the solenoid, circuit, and harness can all be tested.

After any replacements, the mechanic will need to once again reset the trouble codes, restart the vehicle, and check to see if the code remains detected. This will help the mechanic know as soon as the issue is resolved.

Common mistakes when diagnosing the P0973 code

The most commonly made error when assessing the P0973 code comes from a failure to follow the OBD-II trouble code diagnosis protocol. The protocol should be adhered to be mechanics throughout the entire inspection, to make sure that the diagnosis and repairs are efficient. It is fairly common for the shift solenoid to be replaced erroneously, when the actual issue was defective wiring or insufficient transmission fluid.

How serious is the P0973 code?

Usually a vehicle with the P0973 trouble code will still be drivable, though the driver will likely experience transmission problems. Failure to address the P0973 code can result in serious transmission damage, so the vehicle should always be inspected when the code is detected.

What repairs can fix the P0973 code?

Possible repairs for the P0973 trouble code are:

Additional comments for consideration regarding the P0973 code

The P0973 trouble code only applies to vehicles with automatic transmissions. Since the valve A shift solenoid controls different parts of the automatic transmission depending on the make and model of the vehicle, different gears may be impacted in different cars.

Need help with a P0973 code?

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The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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