P0973 - Shift Solenoid "A" Control Circuit Low
OBD2 Error Codes

P0973 - Shift Solenoid "A" Control Circuit Low

13.11.2023 /

P0973 – OBD-II Trouble Code Technical Description

Shift Solenoid "A" Control Circuit Low 

What does the fault code mean P0973?

This trouble code (DTC) is a general transmission diagnostic code that applies to all makes and models of vehicles. The P0973 code is a generic code, but the specific repair steps may vary slightly depending on your specific model.

Trouble code P0973 refers to the shift solenoid valve. In the OBD-II system, it is set when the control module (PCM) detects a low signal level in the shift solenoid valve “A” control circuit.

Transmission solenoid valves play an important role in controlling fluid pressure and proper operation of an automatic transmission. The transmission control module (TCM) receives an electronic signal based on the pressure inside the solenoid valve.

An automatic transmission is controlled by belts and clutches that change gears using fluid pressure at specific locations and times.

Signals from vehicle speed control devices allow the TCM to control the solenoid valves. It directs fluid at the required pressure to various hydraulic circuits, adjusting the gear ratio at the right moment.

During operation, the TCM monitors the solenoid valves, including controlling the resistance and speed sensors. If any of these controls fail, such as due to a shorted solenoid valve, the TCM disables the associated control circuit, storing a P0973 code in the control module memory.

Possible reasons

Trouble code P0973 indicates a problem with the shift solenoid valve “A”. The following are possible reasons for this error:

  1. Solenoid valve “A” malfunction:
    • The solenoid valve itself may be damaged or malfunctioning, resulting in a low signal level.
  2. Wiring and connectors:
    • Short circuits, breaks or damage to the wiring and connectors in the solenoid valve control circuit can cause a low signal level.
  3. Transmission control module (TCM) problems:
    • Faults in the transmission control module, such as damage to electronic components or software, can result in the P0973 code.
  4. Low transmission fluid level:
    • Insufficient transmission fluid level can affect the operation of the solenoid valve and cause an error.
  5. Problems with resistance and speed sensors:
    • The sensors responsible for measuring resistance and speed in the system may be faulty, which will affect the operation of the solenoid valve.
  6. Incorrect power supply:
    • The voltage supplied to solenoid valve “A” may be insufficient due to a power supply problem.
  7. Mechanical problems in the transmission:
    • Some mechanical problems inside the transmission, such as clogged or blocked parts, can cause the solenoid valve to not function properly.
  8. Problems with the car's electrical system:
    • Common problems with the vehicle's electrical system, such as a short circuit or battery problems, can affect the solenoid valve.
  9. Problems with transmission control network:
    • Problems with the transmission control network, including communication failures between various components, can cause P0973.

To accurately determine the cause, it is recommended to carry out additional diagnostics using diagnostic equipment or contact a professional car service.

What are the symptoms of a fault code? P0973?


Symptoms when you have a P0973 trouble code may vary depending on your specific vehicle model and other factors. However, in general terms, the following symptoms may be associated with this code:

  1. Gearshift problems:
    • Slow or unusual gear shifting may be one of the first noticeable symptoms. The automatic transmission may have difficulty changing gears.
  2. Uneven transmission operation:
    • Rough or unstable transmission performance, especially when changing speed or accelerating, may indicate a problem with the solenoid valve.
  3. Drive mode activation delay:
    • When starting the vehicle, you may notice a delay or unusual activation of the Drive mode.
  4. Changes in manual shift mode:
    • If your vehicle is equipped with a manual transmission mode, there may be problems with its operation. For example, difficulties in manual switching.
  5. Check Engine Light Is On:
    • The appearance of the Check Engine light on your dashboard may be the first sign of a problem. The P0973 code will be stored in the system and the indicator will remain illuminated.
  6. Driving restrictions:
    • There may be restrictions in the driving mode, such as activation of the emergency mode or reduced performance.
  7. Fuel Economy Loss:
    • Improper transmission performance can affect your fuel economy, so you may notice increased mileage.
  8. Heavy acceleration or deceleration:
    • The vehicle may respond more slowly to acceleration or deceleration commands due to problems with gear shifting.

If you notice these symptoms or the Check Engine light is on on your dashboard, it is recommended that you take it to a professional auto repair shop to diagnose and fix the problem.

How to diagnose a fault code P0973?

Diagnosing the P0973 trouble code requires a systematic approach and the use of specialized equipment. Here are the steps you can take to diagnose:

  1. Checking the Check Engine indicator:
    • The Check Engine light is illuminated on the instrument panel. The first step is to check other indicators and noticeable symptoms to better understand what problems may be associated with the P0973 code.
  2. Using the diagnostic scanner:
    • Connect the diagnostic scanner to the OBD-II connector in the car. The scanner allows you to read fault codes, as well as data on the operation of the transmission system.
  3. Recording additional codes:
    • In addition to the P0973 code, check to see if there are other trouble codes that may provide additional information about problems in the transmission system.
  4. Checking the transmission fluid level:
    • Check the transmission fluid level according to the manufacturer's recommendations. Low fluid level may affect the operation of the solenoid valve.
  5. Checking wiring and connectors:
    • Carefully inspect the wiring and connectors associated with solenoid valve “A”. Finding damage, shorts or breaks can be a clue to diagnosis.
  6. Checking electrical connections:
    • Make sure all electrical connections in the transmission system, including the transmission control module (TCM), are secure and in good condition.
  7. Diagnosis of solenoid valve “A”:
    • Perform tests to evaluate solenoid valve “A”. Replace or repair it if necessary.
  8. Checking the transmission control module (TCM):
    • Check the transmission control module for problems with electronic components or software.
  9. Testing resistance and speed sensors:
    • Perform tests on the resistance and speed sensors associated with the transmission system.
  10. Checking transmission pressure:
    • If possible, perform transmission pressure tests to evaluate hydraulic system performance.
  11. Additional tests and diagnostics:
    • Depending on the results of the previous steps, additional tests and diagnostics may be needed to identify the specific cause of the problem.

If you do not have experience in diagnosing automotive systems, it is recommended that you contact a professional auto repair shop to accurately diagnose and fix the problem.

Diagnostic errors

When diagnosing the P0973 trouble code, certain common errors may occur. Here are some of them:

  1. Skipping the transmission fluid check:
    • Insufficient level or poor quality transmission fluid can affect the operation of the solenoid valve. Skipping this step may result in missing important information.
  2. Ignoring additional fault codes:
    • Sometimes additional codes occur that can provide additional clues about problems in the transmission system. Ignoring these codes may result in an incomplete diagnosis.
  3. Malfunction in the vehicle's electrical system:
    • Incorrect power supply or malfunctions in the vehicle's electrical system can affect the operation of electronic components. This may be missed with limited electrical inspection.
  4. Skipping sensor tests:
    • Incorrect readings from the resistance and speed sensors can cause problems with the solenoid valve. Misinterpreting tests or skipping them may cause unreliable results.
  5. Incorrect interpretation of scanner data:
    • Data received from a diagnostic scanner may be misinterpreted, especially if the technician is not experienced enough. This may lead to misdiagnosis.
  6. Failed wiring and connector tests:
    • Wiring and connectors can be the cause of solenoid valve problems. Insufficient checking or ignoring the condition of the wiring may lead to missed faults.
  7. Skipping Transmission Control Module (TCM) Checks:
    • Malfunctions in the transmission control module may be missed during diagnosis, which may result in an incomplete repair procedure.
  8. Use of low-quality equipment:
    • The use of low-quality or outdated diagnostic equipment can reduce the accuracy of diagnosis and lead to unreliable results.

To avoid these errors, it is recommended to use professional diagnostic equipment, as well as contact qualified technicians or auto repair shops for accurate diagnosis and repair.

How serious is the fault code? P0973?

Trouble code P0973, indicating problems with the shift solenoid valve “A”, should be taken seriously. The presence of this code can lead to a number of problems with the functioning of the automatic transmission, which affects the overall performance of the vehicle. It is important to consider the following:

  1. Gearshift problems:
    • The P0973 code is often accompanied by shifting problems such as hesitation, uneven shifting, or even failure to shift completely. This can significantly degrade the vehicle's handling.
  2. Possible transmission damage:
    • Delayed or incorrect shifting can cause wear and damage to various transmission components, which may require more extensive and costly repair work.
  3. Potential security risk:
    • Transmission problems can increase the risk of a crash, especially in situations that require precise and timely control of the vehicle, such as overtaking or maneuvering on the road.
  4. Loss of fuel efficiency:
    • The transmission's inability to shift efficiently can also affect fuel economy, resulting in higher fuel costs.
  5. Increased wear on transmission components:
    • Continued use of a vehicle with transmission problems can cause increased wear and tear and additional damage, increasing the amount of repair work required.

Due to the consequences described above, it is recommended to contact a professional car service for diagnostics and repairs. It is important to remember that ignoring trouble codes, especially those related to the transmission, can lead to more serious and costly problems in the future.

What repair will help eliminate the code? P0973?

Troubleshooting the P0973 code involves a number of potential repairs aimed at restoring normal operation of the shift solenoid valve “A” and associated components. Repair steps may vary depending on the specific cause of the problem, but here are some general steps:

  1. Replacing solenoid valve “A”:
    • If tests and diagnostics indicate that the solenoid valve itself is faulty, it may need to be replaced. The new valve must be installed according to the manufacturer's recommendations.
  2. Repair or replacement of wiring and connectors:
    • Check the wiring and connectors associated with solenoid valve “A”. Detection of damage, short circuits or breaks requires repair or replacement of the corresponding sections of the wiring.
  3. Checking and replacing transmission fluid:
    • Make sure the transmission fluid level and quality are correct. If the fluid is contaminated or the fluid level is insufficient, replace it according to the manufacturer's recommendations.
  4. Diagnostics and repair of the transmission control unit (TCM):
    • If a problem is found in the transmission control module, the component may need to be repaired or replaced. If necessary, TCM firmware or software update may also be recommended.
  5. Checking and replacing resistance and speed sensors:
    • Sensors responsible for measuring resistance and speed may require inspection and replacement if they fail.
  6. Checking the power supply:
    • Make sure the power supply to solenoid valve “A” is within normal limits. If necessary, repair the electrical system.
  7. Inspection and repair of mechanical transmission components:
    • Check the mechanical components of the transmission for blockages, wear, or other problems. Repair or replace if necessary.
  8. Additional tests and diagnostics:
    • If repairs do not completely eliminate the problem, additional tests and diagnostics may be required to identify deeper problems.

It is important to note that the exact repair depends on the specific circumstances and diagnostic results. It is recommended that repair work be carried out at a specialized car service center, where experienced technicians can effectively identify and fix the problem.

What is P0973 Engine Code [Quick Guide]

P0973 – Brand-specific information

Trouble code P0973 refers to the shift solenoid valve “A”. The meaning of this code may vary depending on the make and model of the car. Below is a list of several brands with possible interpretations of the P0973 code:

  1. Ford:
    • P0973 – Shift Solenoid Valve “A” – Signal Low.
  2. Chevrolet / GMC:
    • P0973 – Shift Solenoid Valve “A” – Signal Low.
  3. Honda/Acura:
    • P0973 – Shift Solenoid Valve “A” – Signal Low.
  4. BMW:
    • P0973 – Shift Solenoid Valve “A” – Signal Low.
  5. Nissan:
    • P0973 – Shift Solenoid Valve “A” – Signal Low.
  6. Toyota:
    • P0973 – Shift Solenoid Valve “A” – Signal Low.

These are general transcripts and some manufacturers may use slightly different wording. For accurate information on deciphering the P0973 code for a specific vehicle make and model, it is recommended to refer to an official repair manual or consult an authorized service center.

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