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P0742 OBD-II Trouble Code: Torque Converter Clutch Circuit Stuck On

check engine light

P0742 code definition

The P0742 code indicates that the torque converter clutch circuit is behaving in an abnormal manner.

What the P0742 code means

When the P0742 code appears, it means that the amount of torque converter lock up required is not in line with the amount that is actually detected. The transmission control module will detect the slippage on the torque converter clutch when the converter is commanded off. In some cases, this will require several fail cycles before the Check Engine Light illuminates.

What causes the P0742 code?

The P0742 code can be caused by a variety of things. The following are the most common:

  • Dirty transmission fluid
  • Low transmission fluid
  • Faulty torque converter clutch solenoid valve
  • Internal mechanical problem with the transmission
  • Torque converter clutch solenoid valve harness or connectors could be bad
  • Torque converter clutch solenoid valve circuit could be shorted or open

What are the symptoms of the P0742 code?

Symptoms associated with the P0742 code can vary substantially. With some vehicles, the driver might not detect any issues at all. However, in other cases it will no longer be possible for the torque converter clutch to disengage. Some of the other potential symptoms that you might notice with the vehicle include an overheating transmission, transmission slippage, and a more difficult experience when shifting. Many times, the code will be stored and the malfunction indicator light will turn on.

How does a mechanic diagnose the P0742 code?

Mechanics will want to hook up their OBD-II scanner to the vehicle’s onboard computer. The device makes it possible for them to retrieve data about the vehicle and can help with developing a proper diagnosis. Once they have gathered the data, they will reset the code and then test the vehicle. They want to see if the code returned. If it does, they know that it was not tripped in error and that the vehicle has a legitimate issue that needs to be resolved.

Common mistakes when diagnosing the P0742 code

In some cases, there are malfunctions in the torque converter clutch wiring, and these issues are overlooked. The technician instead replaces the lock up solenoids/torque converters when they don’t need replacement.

How serious is the P0742 code?

When a vehicle has the P0742 code stored, it has the potential to be a large problem. The driver might be fortunate and not notice any issues with their vehicle, but that’s not usually the case. The vehicle could have issues when you are shifting, or it can run rough and stall when you are idling. These things are more than just annoying. They have the potential to be dangerous. Whenever you have an issue with your vehicle, whether it’s a large or small problem, make sure you get the repairs you need.

What repairs can fix the P0742 code?

The following are some of the repairs that technicians can make when they are fixing the P0742 code.

  • Check the transmission wiring harness for loose connections and damage.
  • Check the resistance in the torque converter clutch solenoid and internal transmission wiring.
  • If the transmission control module has issues and is causing the codes to be set without reason, the mechanics may need to repair or replace it.

Additional comments for consideration regarding the P0742 code

The majority of the time when the P0742 code comes on the reason is because there is foreign material that is not allowing the proper function of the solenoid or because the fluid is not flowing properly through the transmission valve body. Although some vehicles will not experience any driving issues when this code is present, that is no reason to ignore it. Always have the vehicle diagnosed and serviced by a mechanic who has the knowledge and experience needed to fix this and any other issues your car might have.

Need help with a P0742 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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