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Engine Fault Code P0979

Shift Solenoid C Control Circuit Low

Care Engine Code Reader
The Engine Fault Code P0979 refers to a problem with the shift solenoid C control circuit, indicating that the circuit is low or has an issue. This code is often related to automatic transmissions and can affect how your car shifts gears.

Here`s a breakdown of what it means:

1. Shift Solenoid C: This solenoid controls the flow of transmission fluid, which helps in shifting gears. If its not working properly, it can cause shifting issues.

2. Control Circuit Low: This part of the code indicates that theres a problem with the electrical circuit that powers the solenoid. It could be due to a short circuit, a bad connection, or a faulty solenoid itself.

Possible Causes:
– Faulty shift solenoid C
– Damaged wiring or connectors in the circuit
– Transmission control module (TCM) issues
– Low transmission fluid levels
– Faulty transmission

Alternative Meanings by Manufacturer:
While P0979 generally means the same thing across different makes, some manufacturers might have specific nuances. Here are a few:

1. Porsche: May indicate specific issues with the PDK transmission system.
2. Mini: Could be related to the BMW transmission systems used in Mini models.
3. Mercedes: Might involve more complex transmission systems, and the code could suggest a need for a TCM update.
4. Audi: Similar to VW, where it may indicate issues with the DSG transmission.
5. Jaguar: Could relate to their unique transmission systems, possibly needing a specific diagnostic tool.
6. Land Rover: Might indicate a problem with their Terrain Response system, which can affect shifting.

What to Do:
If you encounter this code, its best to:
– Check the transmission fluid level and condition.
– Inspect the wiring and connectors for damage.
– Consider using a diagnostic tool to get more specific information.
– If needed, consult a professional mechanic familiar with your specific vehicle make and model.

Addressing this code promptly can help prevent further transmission problems down the line.
The Engine Fault Code P0979 refers to a problem with the Shift Solenoid C Control Circuit, specifically indicating a low voltage or an issue in the circuit. This code can appear in various vehicles, including European brands like Porsche, Mini, Mercedes, Audi, Jaguar, and Land Rover. Here are some common causes and manufacturer-specific considerations:

Common Causes:
1. Faulty Shift Solenoid: The solenoid itself may be defective, leading to improper operation.
2. Wiring Issues: Damaged or corroded wiring in the control circuit can cause low voltage.
3. Connector Problems: Loose or corroded connectors can disrupt the electrical flow.
4. Transmission Control Module (TCM) Issues: The TCM may be malfunctioning, affecting solenoid operation.
5. Fluid Issues: Low or contaminated transmission fluid can impact solenoid performance.
6. Internal Transmission Problems: Mechanical issues within the transmission could affect solenoid operation.

Manufacturer-Specific Considerations:
Porsche: Check for specific software updates or recalls that may address transmission issues. Porsche systems can be sensitive to programming.
Mini: Wiring harnesses in some Mini models may be prone to wear, especially in older vehicles.
Mercedes: Many Mercedes vehicles have complex electronic systems, so a diagnostic scan may be necessary to pinpoint the exact fault.
Audi: Audi models might have specific issues with the TCM that require reprogramming or replacement.
Jaguar: Jaguar vehicles often have unique transmission setups, so ensure that the solenoid is compatible with your model.
Land Rover: Some Land Rover models might require a specific procedure for resetting the TCM after repairs.


If you encounter code P0979, it`s essential to perform a thorough inspection of the wiring, connectors, and solenoid itself. Depending on the specific make and model, you may need to consult a service manual or a professional for more detailed diagnostics.
The engine fault code P0979 indicates a problem with the Shift Solenoid C Control Circuit, specifically that the circuit is reading low voltage or has a poor connection. This can affect the transmission`s ability to shift properly. Heres a general approach to fixing this issue, but keep in mind that the exact steps may vary based on the vehicle manufacturer:

General Steps to Fix P0979:

1. Check the Owners Manual: Always start by looking at the vehicles service manual for specific information related to your model.

2. Visual Inspection:
– Wiring and Connectors: Inspect the wiring harness connected to the shift solenoid. Look for frayed wires, corrosion, or loose connections.
– Solenoid Condition: Check the solenoid itself for any visible damage.

3. Test the Shift Solenoid:
– Use a multimeter to check the resistance of the shift solenoid. Compare your readings to the specifications in the service manual.
– If the solenoid is faulty, replace it.

4. Check the Transmission Fluid:
– Low or dirty transmission fluid can cause shifting issues. Check the fluid level and condition. If its low, top it off with the correct type of fluid. If its dirty, consider a fluid change.

5. Inspect the Transmission Control Module (TCM):
– If the solenoid and wiring are fine, the issue might be with the TCM. Check for any fault codes that might indicate a problem with the TCM.

6. Clear the Codes:
– After making repairs, use an OBD-II scanner to clear the fault codes. Then, take the vehicle for a test drive to see if the code returns.

Manufacturer-Specific Notes:

Porsche: Ensure that the transmission software is up to date, as some shifting issues can be resolved with a software update.

Mini: The shift solenoids can be part of a larger assembly. If replacing the solenoid, consider the entire assembly if issues persist.

Mercedes: Mercedes vehicles often have complex transmission systems. If basic checks dont resolve the issue, a professional diagnostic may be needed.

Audi: Audi models may require specific tools for resetting the TCM after repairs. Make sure to follow the manufacturers procedures.

Jaguar: For Jaguars, a common issue is the battery voltage affecting the TCM. Ensure the battery is in good condition.

Land Rover: Land Rover vehicles might have additional electronic components that can affect the solenoid operation. Check for software updates and ensure all modules are communicating correctly.


Addressing the P0979 code requires a systematic approach. Start with visual inspections and simple tests before moving on to more complex diagnostics. If youre unsure or the problem persists, consider consulting a professional mechanic who specializes in your vehicle brand.
Driving with a P0979 code, which indicates a problem with the Shift Solenoid C Control Circuit, is generally not safe. This code suggests that there is an issue with the solenoid that controls gear shifting in your vehicle`s transmission. Heres a breakdown of what this means for different manufacturers:

General Risks:
1. Transmission Issues: You may experience rough shifting, slipping, or even getting stuck in gear.
2. Increased Wear: Continuing to drive could lead to further damage to the transmission.
3. Safety Concerns: If the transmission fails while driving, it could lead to a loss of control.

Manufacturer-Specific Considerations:

1. Porsche:
– Impact: Porsche vehicles often have high-performance transmissions. A malfunction can lead to significant performance issues.
– Avoid driving until the issue is resolved.

2. Mini:
– Impact: Minis may exhibit erratic shifting patterns, which can be uncomfortable and unsafe.
– It`s best to address the issue before driving.

3. Mercedes:
– Impact: Mercedes vehicles might enter a `limp mode,` where power is reduced to protect the transmission.
– Driving in limp mode is possible but not advisable for long distances.

4. Audi:
– Impact: Audis can experience similar limp mode issues, and transmission damage can escalate quickly.
– Get it checked out as soon as possible.

5. Jaguar:
– Impact: Jaguars may also enter a reduced power mode, affecting performance.
– It`s best to stop driving and diagnose the problem.

6. Land Rover:
– Impact: Land Rovers may exhibit erratic shifting and could struggle in off-road conditions.
– Avoid driving until the issue is fixed, especially if you plan to go off-road.


While it might be possible to drive a short distance with this code, it is not recommended. The best course of action is to have the vehicle diagnosed and repaired as soon as possible to avoid more serious damage and ensure your safety.

OBD Codes Explained

Engine Codes

P is for PowerTrain - Engine and Transmission.

P0 Indicates Generic Powertrain Codes

P0 Codes indicate problems with the powertrain and are common for all vehicles using the OBD-II Standard.

P1 Enhanced Manufacturer Specific Codes

P1 Codes are specific to manufacturers.

Sub-System

The 3rd Digit indicates the Sub-System

1 – Emission Management

2 – Injector Circuit

3 – Ignition

4 – Emission Control

5 – Vehicle Speed and Idle

6 – Computer and Output

7 – Transmission

8 – Transmission

9 – Reserved

0 – Reserved

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