Fault code P07A4 is called “Transmission Friction Element “B” Performance/Stuck Off” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P07A4
This diagnostic trouble code (DTC) is a generic transmission code. Error P07A4 is considered a general code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
The problem with the friction element of the transmission is more applicable to automatic transmissions. Symptoms and causes can vary greatly depending on many factors. But it is important to consider the overall condition of the automatic transmission as well as the automatic transmission fluid (ATF).
When the transmission control module activates code P07A4, it also monitors and adjusts other sensors and systems to ensure proper self-diagnosis. Therefore, this problem must be resolved before it causes further potential problems.
It could be an internal electrical fault, such as a short circuit, breakage, or water intrusion.
The letter “B” in this case may indicate several different possibilities. The problem could be with a particular circuit or wire. It could also be a particular friction element in the transmission.
Because of the wide variation in the cause of the error, it is best to consult your service manual for specific locations, differences, and other such characteristics.
Code P07A4 is reported by the PCM or TCM controller when the internal friction element “B” of the transmission is found to be jammed in operation. Also, the friction element may not engage or have other performance issues.
If this error persists, the Malfunction Indicator Light (MIL) will likely illuminate. Some vehicles may require several failure cycles for the MIL indicator light to turn on.
Symptoms of vehicle malfunctions
The main signal that an error P07A4 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
- Transmission slipping.
- Unstable gear shifting.
- Stiff gear shifting or transmission slipping.
- Abnormal shifts in the transmission.
- Low torque.
- Abnormal power output.
- ATF fluid leakage.
The severity of error P07A4 is quite high, so it is recommended to fix the problem as soon as possible. Because ignoring the problem for a long time can lead to more extensive and costly repairs. Over time, the performance of the vehicle may degrade so much that it simply cannot be driven.
Factors that can cause this error code
The error code P07A4 can mean that one or more of the following problems have occurred:
- Worn inner friction element.
- Possible short circuit or wire breakage.
- Contamination or low level of ATF transmission fluid.
- Problem causing uneven rotation speed, such as low tire pressure or brake sticking.
- Different tire sizes.
- Sometimes a faulty PCM or TCM module is the cause.
How to fix or reset OBD-2 code P07A4
Some suggested steps for troubleshooting and fix the error code P07A4:
- Change ATF fluid and filter.
- Fill transmission fluid to required level.
- Flushing to clean inside channels of transmission.
- Wiring check and troubleshooting.
- Troubleshooting mechanical problems inside the transmission.
- Checking connectors as well as wiring.
- Flashing or replacing the PCM or TCM.
Diagnose and repair of problems
Always check the technical service bulletins (TSB) for your particular vehicle first. The P07A4 problem may already be a known problem with a known fix issued by the manufacturer. This can save you time and money during diagnosis.
The next step is to visually inspect the connectors and wiring going to the transmission. Look for scratches, scuffs, exposed wires, burn spots, or melted plastic.
Disconnect the connector and carefully inspect the terminals inside the connector. See if they look burnt or have a green tint indicating corrosion. If you need to clean the terminals, use an electrical contact cleaner and a plastic-bristle brush. Allow to dry and apply electrical grease to the contact areas of the terminals.
Using a diagnostic tool, clear the trouble codes from the memory and see if error P07A4 returns. If the code returns, we will need to test the TFT sensor and associated circuits.
With the ignition key off, disconnect the electrical connectors. Connect a digital voltmeter. The black wire to ground and the red wire to the signal terminal on the wiring harness connector.
Turn on the ignition key. Depending on the manufacturer’s specifications, the voltmeter should show either 12 volts or 5 volts. Jerk the connection and see if the reading changes. If the voltage is incorrect, replace the faulty wires or connector.
Checking the ATF fluid
It is very important that basic maintenance procedures are followed properly. The ATF fluid must be clean and free of debris to avoid similar problems in the future.
If you can’t remember when the transmission was serviced, it is recommended that you have the fluid and filter replaced. There may be debris particles in the old oil that are stuck inside.
When performing maintenance, make sure you are using the correct ATF oil for your particular make and model.
On which vehicles does this problem occur most frequently
Fault code P07A4 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Ford (Fiesta, Focus)
Fault code P07A4 can sometimes be found with other errors. The most common are the following: P079B, P07A5, P2701.