P0740 Code – Meaning, Causes, Symptoms (& How to Fix it)

A guide on how to diagnose & repair problems causing the P0740 trouble code

P0740 Code

The P0740 trouble code appears in your transmission control module when there is a problem with the torque converter clutch circuit.

There could be many causes of this, and in this guide, you will find everything you have to know about the P0740 code.

Code P0740 Definition

P0740: Torque Converter Clutch – Circuit Malfunction

What does the P0740 code mean?

The P0740 code indicates that the transmission control module recognizes an issue with the torque converter clutch circuit.

Automatic cars usually use a converter to transfer the power between the engine and the transmission. This torque converter does actually consists of transmission fluid, which helps the engine to move forward.

For the torque converter to activate, there is a torque converter solenoid controlling it. If the circuit to this solenoid fails, the p0740 code may be stored.

P0740 Trouble Code Symptoms

The most common problem you will notice when the P0740 appears is a check engine light or gearbox light on your dashboard. You will most often not have any shifting or drivability problems, but it can be noticeable in some cases.

The code P0740 symptoms include:

  • Check engine light illuminates
  • A gearbox warning light appears
  • Shifting or drivability issues

Causes of the P0740 Code

The P0740 error code is triggered when there is a problem in the circuit to the Torque converter clutch (TCC) solenoid.

Any of the following problems can trigger the P0740 error code:

  • Faulty Torque converter clutch (TCC) solenoid
  • Faulty Wirings to Torque converter clutch (TCC) solenoid
  • Wiring corrosion to the Torque converter clutch (TCC) solenoid
  • Faulty transmission control module (TCM)

How serious is the P0740 Code?

Medium – In some cases, it happens that you will not notice any problems at all with the trouble code stored.

Unfortunately, this trouble code may cause shifting or driveability problems that can cause you to be stranded on the road. By not repairing the P0740 code, you may also cause other transmission problems in the long run.

What repairs can fix the P0740 code?

  • Replace Torque converter clutch (TCC) solenoid
  • Repair Faulty Wirings to Torque converter clutch (TCC) solenoid
  • Repair or Clean Connector plugs to the Torque converter clutch (TCC) solenoid
  • Replace Transmission control module (TCM)

Common P0740 Diagnosis mistakes

The most common mistake of the P0740 is to think there is a problem with the torque converter itself and maybe replace it.

The p0740 code clearly states a problem with the electrical circuit to the torque converter clutch solenoid and not a problem with the torque converter itself.

Recommended Tools for Diagnosis

How to diagnose the P0740 Trouble Code

Diagnosing the P0740 is often pretty straightforward. You need to find some measure values for your specific car and transmission model, though. You will find these in a repair manual for your car.

  1. Connect an OBD2 scanner and check for any related trouble codes.
  2. Remove the large plug from the transmission (Sometimes this is not possible on some transmission models)
  3. Find which two pins are going to the Torque converter clutch (TCC) solenoid. Ohm, measure these two after the specifications in the repair manual.
  4. If there is an open circuit at the transmission plug or a value far outside of the specs, you need to remove the transmission pan and locate the clutch solenoid. Measure the same on the solenoid when you found the transmission clutch solenoid. Replace if faulty.
  5. If the values seem to be within specifications, make an output test from the transmission control unit with your scanner and measure if it sends 12v+ and ground. If it is not – it may be a wiring problem or a faulty transmission control module.

Estimated Cost of Repair

Here are some examples of common repairs related to the P0442 code. The prices include parts and labor. It does not include diagnosis costs.

  • Torque converter clutch (TCC) solenoid Replacement – 100$ to 300$
  • Transmission Wiring repair – 50$ to 150$

Related P0740 Trouble Codes

P0700: Transmission Control System TCS Malfunction

Common P0740 Related Questions

How to fix P0740 code?

To fix the P0740 code, you need to diagnose a faulty converter clutch solenoid or a wiring issue causing the problem. To do so, you can follow our diagnosis guide in this article.

What causes code P0740?

A faulty converter clutch solenoid most often causes the P0740 code, but in some cases, it can also be caused by bad wirings to it and even a bad transmission control module.

What does P0740 mean?

The p0740 code means that there is a problem in the circuit between the transmission control module and the torque converter clutch solenoid. A faulty solenoid or bad wirings can cause this.

How to clear code P0740?

To clear the P0740 code you need an OBD2 scanner which can read the transmission control module of your car model. Remember that just clearing the trouble code will most likely not fix the issue.

Magnus Sellén
Written by:

Magnus is the owner and main author of Mechanicbase. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.

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