P0979 - Shift Solenoid "C" Control Circuit Low

P0979 – OBD-II Trouble Code Technical Description

Shift Solenoid "C" Control Circuit Low

What does the fault code mean P0979?

Trouble code P0979 indicates a problem with the control of solenoid “C” in the transmission torque converter. More specifically, this code means “Pressure Control Solenoid “C” Control Circuit High.”

This code indicates that the signal in the electrical circuit that controls solenoid C is higher than expected. This can lead to problems with transmission pressure regulation, which in turn can cause various transmission problems.

Possible reasons

Some possible causes of the P0979 code include:

1. Solenoid C fault: Problems with the solenoid valve itself, such as a short circuit or open circuit.
2. Problems with wiring and connectors: Damage, corrosion or open circuit in the electrical circuit connecting the transmission controller and solenoid C.
3. Transmission controller problems: There is a malfunction in the transmission controller that controls the operation of solenoid C.
4. Low voltage in the electrical circuit: This may be caused by problems with the battery, alternator, or other parts of the electrical system.
5. Sensor malfunction: Problems with sensors responsible for monitoring pressure or position inside the transmission torque converter.

Accurate diagnosis requires the use of specialized equipment and may also require testing of the electrical circuits and mechanical components of the transmission. It is recommended that you contact a professional auto mechanic to determine and correct the problem.

What are the symptoms of a fault code? P0979?

Symptoms for trouble code P0979 (Pressure Control Solenoid “C” Control Circuit High) can vary depending on the specific problem with the C solenoid control system. Here are some possible symptoms:

1. Gearshift problems: One of the most common symptoms is incorrect or delayed gear shifting. This may include shifting jerks, shift delays, or other transmission anomalies.
2. Unusual sounds: Problems with the C solenoid can cause unusual noises in the transmission, such as knocking, squeaking, or humming.
3. Errors in engine operation: A high signal level in the solenoid C control circuit can cause the transmission to malfunction, which in turn can affect engine performance. This may include additional loads, changes in idle speed, or even engine errors.
4. Check Engine Light: An illuminated Check Engine light on your dashboard is a typical sign of a problem with the electronic engine and transmission control system. Code P0979 will be stored in the control module memory.
5. Degraded performance and fuel consumption: Transmission problems can affect the overall performance of the vehicle and lead to increased fuel consumption.

If you notice these symptoms or the Check Engine Light illuminates on your dashboard, it is recommended that you contact a qualified auto mechanic to diagnose and repair the problem.

How to diagnose a fault code P0979?

To diagnose trouble code P0979 (Pressure Control Solenoid “C” Control Circuit High), the following approach is recommended:

1. Scanning error codes: Use a diagnostic scan tool to read error codes in the electronic engine and transmission control system. The P0979 code will indicate a specific problem with solenoid C control.
2. Visual check of wires and connectors: Carefully inspect the wires and connectors associated with solenoid C. Check for damage, corrosion, or breaks. Disconnect and check the connectors for signs of poor contact.
3. Resistance measurement: Using a multimeter, measure the resistance in the solenoid C control circuit. The normal resistance may be listed in the service manual for your specific vehicle make and model.
4. Checking Solenoid C: Check solenoid C itself for corrosion, breaks or other mechanical damage. If necessary, replace the solenoid.
5. Checking transmission pressure: Use a diagnostic scan tool to monitor transmission pressure while the vehicle is running. High pressure may be due to problems with solenoid C control.
6. Checking sensors and sensors: Check the operation of transmission-related sensors such as position and pressure sensors.
7. Checking the electrical transmission system: Check transmission control system components, such as the transmission controller, for damage or malfunction.
8. Professional diagnostics: If you cannot identify and fix the problem yourself, it is recommended that you contact a professional auto mechanic or service center. They may use more advanced diagnostic methods, such as testing using special equipment.

It is important to note that diagnosing and repairing transmissions requires certain skills and experience, so if you do not have the relevant experience, it is better to turn to professionals.

Diagnostic errors

When diagnosing trouble code P0979 (Pressure Control Solenoid “C” Control Circuit High), certain common errors may occur. Some of them include:

1. Skip visual inspection of wires and connectors: Sometimes technicians may miss important details when visually inspecting wires and connectors. Damage, corrosion or breaks may be missed, making diagnosis difficult.
2. Unreported problems with solenoid C: The error may be caused by a faulty solenoid C itself. Some technicians may focus on the wires and connectors without paying attention to the solenoid's own condition.
3. Ignoring other error codes: Sometimes problems in the electronic system can cause multiple error codes. Ignoring additional codes may result in missing key information about the problem.
4. Unstable contact in connectors: Connections and connectors may experience problems such as oxidation or unstable contact. This may result in incorrect signals or open circuits.
5. Insufficient transmission pressure check: High transmission pressure may be the cause of the P0979 code. Insufficient pressure testing may result in pressure problems being missed.
6. Unaccounted environmental factors: Electromagnetic interference or other environmental factors can affect electrical components and may be missed during diagnosis.
7. Transmission controller malfunctions: Problems with the transmission controller can cause trouble code P0979. A thorough diagnosis of all elements of the transmission control system is important.

For successful diagnosis, a systematic approach is recommended, including visual inspection, resistance measurements, pressure checks, and consideration of all possible factors affecting the operation of the C solenoid and the transmission as a whole. If you do not have experience in diagnosing transmissions, it is better to turn to professionals.

How serious is the fault code? P0979?

Trouble code P0979 (Pressure Control Solenoid “C” Control Circuit High) indicates a high signal level in the transmission pressure solenoid control circuit C. The severity of this code can vary depending on several factors:

1. Impact on transmission: Problems with solenoid C control can result in improper transmission pressure regulation. This, in turn, can cause improper shifting, jerking, hesitation, and other transmission problems.
2. Increased risk of damage: If the problem is not resolved, high transmission pressure can cause increased wear on transmission components, leading to more severe damage and possibly more expensive repairs.
3. Fuel consumption: An improperly functioning transmission can affect fuel economy as the vehicle may operate less efficiently.
4. Check Engine Light: The inclusion of the Check Engine light can also affect the overall diagnostics of the vehicle and cause dissatisfaction with the technical condition.
5. Possible performance issues: Transmission problems can affect the overall performance of the vehicle, which is important for a comfortable and safe driving experience.

Overall, code P0979 should be taken seriously. If the Check Engine light illuminates on your dashboard and you notice abnormal transmission performance, it is recommended that you take it to a qualified mechanic to diagnose and resolve the problem. Malfunctions in the transmission control system can lead to serious consequences, so it is recommended to react quickly.

What repair will help eliminate the code? P0979?

Resolving the P0979 trouble code involves resolving the issue that caused the solenoid C control circuit to be high. Here are a few steps that may help resolve this issue:

1. Solenoid C replacement: If solenoid C is truly bad, it should be replaced. Replacing the solenoid requires specific procedures and may vary depending on the transmission design.
2. Checking and repairing wiring and connectors: Carefully check the wiring and connectors associated with solenoid C. If damage, corrosion, or broken wires are found, they can be repaired or replaced.
3. Checking transmission pressure: Measuring transmission pressure can be a key diagnostic step. Check the transmission pressure in various vehicle operating modes. Pressure adjustments or replacement of pressure control parts may be necessary.
4. Replacing the transmission controller: If the problem is with the transmission controller, it may need to be replaced or programmed. Transmission controllers can be rebuilt, but sometimes require replacement.
5. Checking sensors and sensors: Check transmission-related sensors such as pressure or position sensors. Replacing faulty sensors may resolve problems.
6. Diagnosis of mechanical problems: If transmission problems are related to mechanical components, such as clutches or friction plates, mechanical intervention may be required.

It is recommended to conduct a detailed diagnosis using specialized equipment and tools. If you are not experienced in transmission repair, it is recommended that you take it to a professional mechanic or service center for an accurate diagnosis and repair.

What is P0979 Engine Code [Quick Guide]

P0979 – Brand-specific information

Trouble codes, including P0979, may have similar meanings for different makes of vehicles. However, it is recommended that you refer to the manufacturer's official service manuals or consult your dealer for accurate information. Here are some examples of decryptions for various brands:

1. Ford, Lincoln, Mercury:
   • P0979: Shift Solenoid “C” Control Circuit High
2. Chevrolet, GMC, Cadillac, Buick:
   • P0979: Shift Solenoid “C” Control Circuit High
3. Toyota, Lexus:
   • P0979: Shift Solenoid “C” Control Circuit High
4. Honda, Acura:
   • P0979: Shift Solenoid “C” Control Circuit High
5. Nissan, Infiniti:
   • P0979: Shift Solenoid “C” Control Circuit High
6. Volkswagen, Audi, Porsche:
   • P0979: Shift Solenoid “C” Control Circuit High
7. BMW, Mini:
   • P0979: Shift Solenoid “C” Control Circuit High
8. Mercedes Benz:
   • P0979: Shift Solenoid “C” Control Circuit High
9. Subaru:
   • P0979: Shift Solenoid “C” Control Circuit High
10. Hyundai, Kia:
    • P0979: Shift Solenoid “C” Control Circuit High

Remember that these definitions may vary depending on the specific model and year of the vehicle, so it is important to refer to the resources provided by the manufacturer for accurate information.