P0779 Intermittent / unstable signal in the automatic transmission pressure control solenoid valve “B” circuit
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P0779 – Technical description of the OBD-II fault code
Trouble code P0779 is a common transmission-related trouble code that indicates an intermittent/intermittent signal in the transmission pressure control solenoid valve B circuit.
What does the fault code mean P0779?
Trouble code P0789 indicates a problem with the transmission pressure control solenoid valve. This usually means that the transmission pressure control solenoid valve “C” has failed or has a problem with its circuit.
In vehicles with an automatic transmission controlled by the engine control module (PCM), pressure control solenoid valves are used to regulate transmission pressure. This is necessary to ensure proper gear shifting and optimal transmission performance.
When the P0789 code appears, a number of problems may occur, including difficulty shifting, jerking, or erratic transmission. It is important to contact a qualified auto mechanic or auto repair shop to diagnose and fix this problem.
Possible reasons
Trouble code P0779 indicates a problem with the transmission pressure control solenoid valve, possible causes of this fault are:
- Solenoid valve failure: The valve itself may be damaged, stuck, or have problems with its sealing elements, preventing it from functioning properly.
- Electrical circuit problems: The wiring, connectors, or electrical circuit associated with the solenoid valve may have breaks, corrosion, or other damage, causing the signal to not be transmitted correctly from the PCM to the valve.
- Problems with the engine control module (PCM): A malfunctioning PCM can cause erroneous signals to be sent to the pressure control solenoid valve.
- Transmission fluid pressure problems: Insufficient transmission pressure can cause P0779. This may be caused by a fluid leak, a clogged filter, or other problems in the transmission hydraulic system.
- Problems with other transmission components: For example, faults in other pressure control solenoid valves or other internal transmission components can cause P0779.
To accurately determine the cause of the malfunction, it is recommended to carry out diagnostics using a scanner to detect the P0779 code and further analyze the transmission parameters.
What are the symptoms of a fault code? P0779?
Symptoms for a P0779 trouble code can vary depending on the specific problem and vehicle characteristics, but some possible symptoms include:
- Gear shifting problems: The vehicle may have difficulty shifting gears or shift erratically. This may manifest itself as a delay in shifting gears or irregular transmission behavior.
- Jerks or jolts when shifting gears: There may be a jerk or shock when shifting gears, especially when accelerating or decelerating.
- Unusual sounds or vibrations: Unusual noise or vibration may be noticed when the transmission operates, which may indicate problems with its normal function.
- Loss of power: The vehicle may lose power or exhibit less efficient acceleration due to improper transmission pressure management.
- Illuminates the Check Engine indicator: When the PCM detects a problem with the pressure control solenoid valve, it will activate the Check Engine Light on the vehicle's instrument panel, accompanied by a P0779 trouble code.
- Emergency operation mode (limp mode): In some cases, when a serious problem is detected, the vehicle may go into limp mode to prevent further damage, which may involve speed limits or other restrictions.
It is important to remember that these symptoms can also be combined with other problems, so it is recommended that you contact a qualified auto mechanic or auto repair shop for an accurate diagnosis and troubleshooting.
How to diagnose a fault code P0779?
Trouble code P0779 can be diagnosed as follows:
- Checking the error code: Use a diagnostic tool to read the P0779 trouble code from the engine control module (PCM) memory.
- Checking the Physical Condition of the Pressure Control Solenoid Valve: Check the valve for physical damage, leaks or other visible problems.
- Electrical circuit check: Using a multimeter, check the electrical circuit, connections and connectors associated with the solenoid valve. Make sure the wires are not broken, the connectors are securely connected, and there are no signs of corrosion.
- Checking the resistance of the solenoid valve: Using a multimeter, measure the resistance of the solenoid valve. Compare the resulting value with the manufacturer's recommended specifications.
- Voltage test: Measure the voltage at the solenoid valve according to the manufacturer's specifications.
- Checking transmission fluid pressure: Check the transmission fluid pressure using special equipment. Low pressure may be due to problems in the pressure control system.
- PCM diagnostics: If all of the previous steps fail to determine the cause of the problem, you may need to diagnose the engine control module (PCM) using specialized equipment.
- Checking other transmission components: Check other transmission components, such as pressure sensors, other solenoid valves, or internal mechanisms, for problems.
After diagnosing and identifying the cause of the malfunction, you can begin to repair or replace the faulty components.
Diagnostic errors
When diagnosing DTC P0779, the following errors may occur:
- Incorrect replacement of the solenoid valve: Sometimes mechanics may jump right into replacing a solenoid valve without conducting sufficient diagnostics. This can result in unnecessary costs for parts and labor.
- Ignoring the electrical circuit: Some mechanics may focus only on the valve itself without checking the electrical circuit, connections and connectors. Skipping this step may result in an incorrect diagnosis.
- Incorrect cause identification: Mechanics may assume that the problem is necessarily related to the solenoid valve, without considering other possible causes, such as problems with transmission fluid pressure or the PCM signal.
- Faulty PCM Diagnostics: Sometimes the problem may be due to a problem with the engine control module (PCM) itself. Omitting this aspect may lead to misdiagnosis and unnecessary replacement of components.
- Insufficient inspection of other transmission components: The problem may not only be caused by the solenoid valve, but also by other transmission components such as pressure sensors or hydraulic mechanisms. They also need to be checked.
- Misinterpretation of data: Errors may occur due to incorrect interpretation of test results or diagnostic data.
It is important to carry out a comprehensive diagnosis, taking into account all possible causes of the problem, in order to avoid mistakes and correct the malfunction.
How serious is the fault code? P0779?
Trouble code P0779 should be taken seriously as it indicates a problem with the vehicle's transmission pressure control solenoid valve. Depending on the specific cause, this error code may have varying degrees of severity:
- Possible problems with the gearbox: A malfunction of the pressure control solenoid valve may cause the transmission to malfunction or even break down. This may cause difficulty shifting, jerking or loss of power.
- Risk of transmission damage: If the problem is not corrected in time, it may cause damage to other transmission components due to improper system pressure management.
- Driving restrictions: In some cases, if the monitoring system detects a serious malfunction, it may put the vehicle into limp mode, which may limit its performance and speed.
- Potential Security Issues: Incorrect transmission operation can affect vehicle handling and increase the risk of an accident, especially when driving at high speeds or in difficult traffic conditions.
Based on this, the P0779 trouble code should be considered serious and it is recommended that you contact a qualified auto mechanic or auto repair shop to diagnose and repair the problem as soon as possible. It is not recommended to ignore this error code as it may lead to further problems and increase risks to the safety and reliability of the vehicle.
What repair will help eliminate the code? P0779?
Resolving the P0779 trouble code may require different repair steps, depending on the specific cause of the problem. Here are some possible repair methods:
- Replacing the Pressure Control Solenoid Valve: If the problem is related to the valve itself, it will likely need to be replaced. This involves removing the old valve and installing a new one that meets the manufacturer's specifications.
- Electrical circuit repair: If the problem is related to the electrical circuit, the problem must be found and corrected. This may include replacing damaged wires, repairing connectors, or updating electrical contacts.
- Servicing or replacing other transmission components: If the problem is not directly related to the solenoid valve, other transmission components, such as pressure sensors, hydraulic mechanisms, or internal parts, may need to be serviced or replaced.
- Engine Control Module (PCM) Software Update: Sometimes the problem may be related to the PCM software. In this case, the PCM may need to be updated or reprogrammed.
- Checking and servicing transmission fluid pressure: Incorrect transmission pressure can also cause P0779. Check and service transmission fluid pressure as necessary.
It is important to remember that in order to accurately identify and fix the problem, it is recommended to contact a qualified auto mechanic or car service center. Improper repairs may lead to additional problems or re-occurrence of the error.
P0779 – Brand-specific information
The specific meaning of the P0779 trouble code may vary depending on the vehicle manufacturer. Here are some examples for different car brands:
- Toyota / Lexus:
- P0779: Pressure control solenoid valve "B" signal intermittent.
- Ford:
- P0779: Pressure control solenoid "B" - intermittent signal.
- Chevrolet / GMC:
- P0779: Pressure control solenoid valve "B" signal intermittent.
- Honda/Acura:
- P0779: Pressure control solenoid valve "B" signal intermittent.
- Nissan/Infiniti:
- P0779: Pressure control solenoid "B" - intermittent signal.
- Hyundai/Kia:
- P0779: Pressure control valve 3 error.
- Volkswagen/Audi:
- P0779: Pressure control solenoid valve "B" signal intermittent.
- BMW:
- P0779: Pressure control solenoid "B" - intermittent signal.
- Mercedes-Benz:
- P0779: Pressure control solenoid valve "B" signal intermittent.
- Subaru:
- P0779: Pressure control solenoid "B" - intermittent signal.
These are just general decodings of the P0779 code for various car brands. For your specific vehicle model and year, it is recommended that you consult the manufacturer's documentation or contact a qualified auto mechanic for more detailed information and diagnosis.
