Description of the P0749 fault code.
OBD2 Error Codes

P0749 Intermittent / unstable signal in the automatic transmission pressure control solenoid valve “A” circuit

26.05.2022 /

P0749 – OBD-II Trouble Code Technical Description

Trouble code P0749 indicates an intermittent/intermittent signal in the transmission pressure control solenoid valve “A” circuit.

What does the fault code mean P0749?

Trouble code P0749 indicates a problem with the transmission fluid pressure control solenoid valve “A” in an automatic transmission vehicle. This code indicates that there is insufficient voltage at the solenoid valve, which can lead to improper transmission operation and other transmission problems. The solenoid valve regulates transmission fluid pressure, and if its electrical circuit is not in stable contact, there may not be enough pressure to shift gears.

Fault code P0749.

Possible reasons

Some possible reasons for the P0749 trouble code:

  • Pressure control solenoid valve malfunction: The valve itself may be damaged or malfunctioning due to wear, corrosion or other problems.
  • Wiring and electrical connections: Loose connections, breaks or shorts in wiring, connections or connectors can cause insufficient voltage to the solenoid valve.
  • Problems with the transmission control unit: Malfunctions or malfunctions in the transmission control module (TCM) can cause erroneous signals or improper control of the solenoid valve.
  • Power problems: Insufficient power supply or problems with the vehicle's battery may cause electronic components, including the solenoid valve, to malfunction.
  • Pressure sensors or other transmission sensors: Malfunctions or malfunctions in transmission fluid pressure sensors or other transmission-related sensors can cause pressure control errors.
  • Problems with the gear shift mechanism: Faults in the gear shift mechanism, such as due to wear or damage, can also cause P0749.

These causes can be tested and diagnosed with specialized equipment and vehicle maintenance.

What are the symptoms of a fault code? P0749?

Some common symptoms that may occur when trouble code P0749 is present:

  • Gear shifting problems: The vehicle may experience difficulty or delay when shifting gears. This may manifest itself as difficulty shifting from one gear to another or jerking when shifting.
  • Unusual noises: A strange sound or noise may be produced from the transmission area, especially when shifting gears or when the transmission is operating.
  • Unusual engine behavior: Engine roughness or changes in engine speed when shifting gears may occur.
  • Check Engine Light: The appearance of a Check Engine Light or similar warning lights on your dashboard may indicate a problem, including Trouble Code P0749.
  • Performance degradation: In case the transmission is not working properly due to a solenoid valve problem, it may cause the overall performance of the vehicle to deteriorate.

If you notice any of these symptoms, especially in conjunction with the P0749 trouble code, it is recommended that you have your transmission diagnosed and repaired by a professional.

How to diagnose a fault code P0749?

To diagnose DTC P0749, you can follow these steps:

  1. Checking Error Codes: Using a vehicle diagnostic tool, read the error codes from the PCM memory. In addition to the P0749 code, also look for other trouble codes that may be related to transmission or electrical systems.
  2. Visual inspection: Inspect the electrical connections and wires associated with the pressure control solenoid valve. Check them for damage, corrosion or breaks. Make sure all connections are tight and secure.
  3. Solenoid valve test: Using a multimeter, check the voltage at the pressure control solenoid valve according to the manufacturer's recommendations. If the voltage is outside the normal range or missing, there may be a problem with the valve or its electrical circuit.
  4. Checking transmission fluid pressure: Check the transmission fluid pressure using a special pressure gauge according to the vehicle specifications. Low pressure may indicate problems with the solenoid valve or other transmission components.
  5. Additional tests and studies: Depending on the results of the previous steps and the manufacturer's specifications, additional tests may be required, such as checking resistance in electrical circuits, checking pressure sensors, etc.

If you are unsure of your diagnostic skills or do not have the necessary equipment, it is recommended that you contact a qualified mechanic or auto repair shop for further analysis and repair.

Diagnostic errors

When diagnosing DTC P0749, the following errors may occur:

  • Skipping a visual inspection: Failure to perform a detailed visual inspection of electrical connections and wiring may result in missing damage or corrosion that may be causing the problem.
  • Insufficient solenoid valve check: Solenoid valve tests may be incorrect or incomplete. Make sure the test includes measuring voltage, resistance, and checking valve operation in accordance with the manufacturer's recommendations.
  • Ignoring other components: Sometimes the problem may not only be with the solenoid valve, but also with other transmission components such as pressure sensors or the transmission control module (TCM). Ignoring other potential causes may lead to misdiagnosis.
  • Insufficient transmission fluid pressure check: If the transmission fluid pressure is not checked, important information about the condition of the transmission may be missed, which may result in an incorrect diagnosis.
  • Misinterpretation of results: Incorrect interpretation of diagnostic results, especially when using specialized equipment, can lead to incorrect conclusions about the causes of the problem.

To prevent these errors, it is important to carry out diagnostics methodically, carefully following the manufacturer's recommendations and paying attention to all details and aspects of the transmission system.

How serious is the fault code? P0749?

Trouble code P0749 indicates a problem with the transmission fluid pressure control solenoid valve. Although this is not a critical failure, it can cause serious problems with the transmission and affect its performance and durability.

Low or insufficient transmission fluid pressure caused by a faulty solenoid valve can lead to poor shifting, increased wear on transmission components, and even failure due to overheating or malfunction. Additionally, transmission problems can reduce the overall safety and handling of the vehicle.

Overall, while P0749 is not a fatal fault, it does require careful attention and timely repair to avoid more serious transmission problems and ensure a safe and reliable drive.

What repair will help eliminate the code? P0749?

The following repair measures may be required to resolve DTC P0749:

  1. Replacing the Pressure Control Solenoid Valve: If the problem is due to the valve itself not working properly, it should be replaced. When replacing a valve, it is important to ensure that the new valve meets the manufacturer's specifications and is installed correctly.
  2. Repair or replacement of electrical connections and wires: If the problem is due to improper communication or electrical problems in the control circuit, then the damaged connections or wires must be checked and, if necessary, repaired or replaced.
  3. Diagnostics and repair of other transmission components: Sometimes the problem may not only be with the solenoid valve, but also with other transmission components such as pressure sensors or the transmission control module (TCM). After a thorough diagnosis, these components should be repaired or replaced.
  4. Transmission fluid maintenance and replacement: If possible, it is also recommended to change the transmission fluid and filter. This can help improve transmission performance and prevent problems from recurring.
  5. Professional diagnostics and repair: If experience is lacking or specialized equipment is required, repairs may require professional intervention by a qualified mechanic or auto mechanic.

It is important to consider the vehicle manufacturer's recommendations and follow service and repair recommendations to correctly correct the problem and ensure reliable transmission operation.

What is P0749 Engine Code [Quick Guide]

P0749 – Brand-specific information

Trouble code P0749 can occur on vehicles of various makes and models, code decoding for some popular brands:

These are just some of the possible interpretations of the P0749 code for various makes of vehicles. It is important to note that the specific meaning of the code may vary depending on the model, year of manufacture and other factors. Therefore, it is always recommended to refer to the manufacturer's documentation or consult a qualified technician when interpreting a DTC.

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