OBD-II Trouble Code Technical Description
The code indicates that there is a detected slip in the transmission friction element F.
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) that applies to OBD-II vehicles with automatic transmissions. This includes vehicles from various manufacturers such as Chevrolet, GMC, Toyota, VW, Ford, Honda, Dodge, Chrysler, etc. The specific repair steps may vary depending on the year, make, model, and powertrain configuration.
The description of “transmission friction element” is quite vague considering the complexity of an automatic transmission’s mechanical operation. It’s important to note that manual transmissions also use similar friction materials, such as clutches.
In this case, it is likely referring to an automatic transmission. The symptoms and causes can vary significantly, but it is crucial to consider the overall health of the automatic transmission and the condition of the Automatic Transmission Fluid (ATF).
Problems with the internal friction materials in the automatic transmission can lead to erratic driving conditions, including issues with shift timing, torque output, and other consequences. Factors such as unevenly paired tires or inadequately inflated tires can cause internal slippage due to their unsymmetrical circumstances. It’s important to keep this in mind when assessing the functionality of the drivetrain and troubleshooting any faults. Have you recently installed a used tire? Is it the same size as the others? Verify this by checking the tire’s sidewall. Minor differences can sometimes cause indirect issues like this.
When the Engine Control Module (ECM) activates this P079F code and related codes, it proactively monitors and adjusts other sensors and systems to ensure proper self-diagnosis. Therefore, it is crucial to address this issue before it potentially leads to further problems. It may be a simple fix, but it could also be a complex internal electrical malfunction, such as a short, open circuit, or water intrusion. Seek appropriate help to avoid costly mistakes, even professionals can overlook certain issues.
The letter “F” in this case may refer to a specific circuit/wire or a specific friction element within the transmission. Always consult your service manual for specific locations, distinctions, and other specifications.
Code P079F indicates slip in the internal “F” friction element inside the transmission.
What is the severity of this DTC?
As mentioned earlier, it is not advisable to leave this issue unattended, especially if you are actively using the vehicle with the fault(s) present. It should be prioritized, especially if you rely on the vehicle for daily transportation.
Photo and cutaway of an automatic transmission:
What are some of the symptoms of the code?
Symptoms of a P079F trouble code may include:
What are some of the common causes of the code?
Causes for this P079F friction element slip code may include:
What are some P079F troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins for known issues with the specific vehicle.
Advanced diagnostic steps become very vehicle specific and may require the appropriate advanced equipment and knowledge to perform accurately. We include basic steps below but refer to a vehicle year/make/model/powertrain specific repair guide for specific steps for your vehicle.
Basic Step #1
It is crucial to follow basic maintenance procedures, starting with the transmission fluid. The ATF needs to be clean and free of debris. It is also important to adhere to proper maintenance schedules to prevent future faults. If you can’t remember the last time the transmission was serviced (i.e., filter+fluid+gasket), it is recommended to perform this service before proceeding. There may be debris trapped internally that can be resolved with a simple service, so make sure you know when the last A/T service was performed.
NOTE: Ensure you are using the correct ATF for your specific make and model.
Basic Step #2
When trying to locate the connector/harness for this system, you will likely need to find a junction connector. There may be one “master” connector, so refer to your manual to ensure you are working with the correct one. Make sure the connector is properly seated to establish a good electrical connection. The location of the connector on the A/T may subject it to vibrations that could loosen connections or cause physical damage. Additionally, there is a possibility of ATF saturating connectors and wires, leading to present or future issues.
Basic Step #3
It is always wise to consider the overall condition of your vehicle. Other systems can directly affect the transmission and vice versa. Uneven tires, worn suspension parts, and incorrect wheels can cause issues in this system and potentially others. Ensure everything is balanced to potentially resolve this code.
This article is strictly for informational purposes, and the technical data and service bulletins for your specific vehicle should always take precedence.
