Fault code P0749 is called “Pressure Control Solenoid “A” Intermittent” 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 P0749
This diagnostic trouble code (DTC) is a generic code. Error P0749 is considered a generic code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
Fault code P0749 OBD-II is set when the control module (PCM) has detected a problem with the transmission pressure control solenoid “A” valve. Most automatic transmissions have at least three valves that are labeled A, B and C.
The code set is based on a specific fault that alerts the PCM and turns on the check engine light.
The transmission pressure control solenoid valves are used to control fluid pressure and proper operation of the automatic transmission. The PCM receives an electronic signal based on the pressure inside the solenoid valve. The automatic transmission is controlled by belts and clutches that shift gears by applying fluid pressure at the right place at the right time.
Based on signals from related devices that control vehicle speed, the PCM controls the pressure solenoid valves. To direct the fluid at the proper pressure to the various hydraulic circuits. Which change the transmission ratio at the right time.
Code P0749 is set by the PCM when the pressure control solenoid valve “A” is working intermittently.
Symptoms of vehicle malfunctions
The main signal that an error P0749 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 written to the ECM memory as a fault).
- The vehicle goes into emergency mode.
- The transmission slips when shifting gears.
- Transmission is stuck in gear.
- Hard gear shifting.
- Transmission overheating.
- Increased fuel consumption.
- Possible symptoms similar to ignition skips.
The severity of fault code P0749 is usually moderate, but can quickly escalate to a more serious level if not corrected in a timely manner.
Factors that can cause this error code
The error code P0749 can mean that one or more of the following problems have occurred:
- The pressure control solenoid valve is defective.
- Contaminated fluid or clogged transmission filter.
- Low transmission fluid level.
- Transmission fluid passages are clogged.
- Faulty transmission pump or transmission valve housing.
- Other mechanical problems inside the transmission.
- A wiring problem or damaged connector.
- In rare cases, PCM malfunction.
How to fix or reset OBD-2 code P0749
Some suggested steps for troubleshooting and fix the error code P0749:
- Change ATF fluid and filter.
- Fill transmission fluid to required level.
- Flushing to clean internal ducts of the transmission.
- Test, if necessary replace faulty pressure control solenoid valve.
- Repair or replace faulty transmission pump and transmission valve housing.
- Check connectors as well as wiring.
- Flash or replace PCM.
Diagnose and repair of problems
Before you begin the process of troubleshooting P0749, you should research the Technical Service Bulletins (TSBs) for your particular vehicle. In some cases, this can save a lot of time by pointing you in the right direction.
Next, you should check the fluid level and check for contamination. Before replacing the fluid, you should check the vehicle’s records to see when the filter and fluid were last changed.
After that, you should do a detailed visual inspection to check the condition of the wiring for obvious defects. Check the connectors and wiring to the transmission pressure control solenoid valve, transmission pump and PCM. Depending on the configuration, the transmission pump may be electrically or mechanically driven.
Normal readings for wiring and connections should be 0 ohms of resistance. Wiring continuity checks should always be performed with power disconnected from the circuit. To avoid short-circuiting and creating additional damage.
Resistance or lack of continuity indicates faulty wiring that is open or shorted. In this case, repair or replacement will be required.
On which vehicles does this problem occur most frequently
Fault code P0749 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
Fault code P0749 can sometimes be found with other errors. The most common are the following: P0745, P0746, P0747, P0748.