Do you have problems with the P0740 error code?
In this article we will discuss what this error code means and how you can find the problems to fix them.
We start with the meaning of the P0740 error code and possible symptoms.
What Does the P0740 Code Mean?
Code P0740 indicates that the Powertrain Control Module (PCM) has observed unusual behavior within the torque converter clutch circuit.
Any vehicle built since 1996 will return this common fault code if a problem is detected with the torque converter clutch circuit. However, modern vehicles today determine when this code must be given based on other information such as throttle position, engine load, vehicle speed, etc.
Initially, you will not notice any symptoms if a problem occurs with the torque converter clutch. However, if the problem persists and is ignored for a long time, your converter clutch may fail completely and also disrupt engine performance. Common symptoms include:
- Check engine light illuminates
- Fall in fuel economy
- Torque converter clutch fails to engage
- Trouble when shifting gears
- Transmission overheating
- Engine stalling
- Transmission gets stuck in a single gear
- Car fails to move when in gear
- Engine misfire
Possible P0740 Causes
Error code P0740 can be triggered for many reasons. Among the most common causes are:
- Damaged torque converter lockup solenoid
- Defective torque converter or clutch
- Internal damage within the transmission
- Faulty valve body
- Low transmission fluid level
- Non-functioning engine coolant temperature sensor
- Damaged wiring
Possible P0740 Solutions
The first step should be to check the wiring and connection of the torque converter clutch leading to the PCM. Most of the time, it’s all about the wiring and the bad connection, while the mechanics will take your money by claiming a huge problem. If the problem is not related to the wiring, look for the following solutions:
- Repair and replace the torque converter clutch solenoid
- Replace torque converter clutch
- Check and replace transmission fluid
- Repair powertrain control module
- Replace the transmission system
|P0740 Trouble Code||Check engine light illuminates
Drop in Fuel Economy
Torque Converter Clutch fails to engage
Trouble when shifting Gears
Transmission gets stuck in a single gear
Car fails to move when in gear
|Damaged Torque Converter Lockup Solenoid
Defective Torque Converter or Clutch
Internal Damage within the Transmission
Faulty Valve Body
Low Transmission Fluid Level
|Repair and replace the Torque Converter Clutch solenoid
Replace Torque Converter Clutch
Check and replace transmission fluid
Repair powertrain control module
Replace the transmission system
How to Diagnose the P0740 Code?
The P0740 code can be a little difficult to diagnose at first, but can be observed when the car has driveability problems. You will need to have a factory wiring diagram of your car to find the correct connection points between the circuitry and detect wiring damage. You should also check the transmission oil.
Here are some steps you should follow to diagnose the P0740 code.
Connect a Car Battery Charger
It is important that your vehicle’s battery does not discharge while you are working on troubleshooting the error codes. It is therefore important that you attach a car battery charger when working on your vehicle with the ignition on. In addition, a weak battery can also generate additional fault codes, which makes the situation even more confusing.
Connect the OBD2 Scanner
To read the information generated by the error codes an OBD2 Code Scanner is required. This device allows you to easily read the data from the error code and also has built-in values that you can use to make a comparison and determine the cause of the problem. You will also need a digital volt-ohm meter to test the circuit resistance.
Check the Wire Connections
The most important first step is to determine whether a bad connection or wiring is causing the P0740 error code to be generated. Examine the wiring leading to the transmission system and look for signs of damage. Refer to the vehicle’s factory wiring diagram for easy identification of all connection points.
Check Transmission Fluid
If you have checked the wiring and the connections leading to the transmission system and everything seems to be in order, check the transmission oil for its correct level and condition. If the fluid appears to be less or different to the norm, this may be part of the problem.
Check Resistance of TCC Solenoid
First remove the connector of the transmission system wiring harness and then check the resistance of the TCC magnet with the DVOM. If the displayed resistance is too high, there may be something wrong with the solenoid coil.
TCM can be monitored with an advanced diagnostic tool, and it requires some expertise to understand the reading. It is advisable to take your car to an automotive specialist who will perform this test and let you know if the problem is related to TCM.
Transmission Torque Converter Clutch Solenoid Replacement
In most vehicles, the transmission solenoid valve is located in the oil sump and is connected to the valve body. In such a case, a car expert can easily replace the damaged switching solenoid. However, on some vehicles, the transmission solenoid valve is packed in several units, and if a problem occurs, the entire package must be replaced.
The average cost of replacing a single transmission solenoid is between $20 and $100, and an entire package can cost about $200. Labor costs are about $150 to $400.
Does the P0740 Code Need Serious Attention?
The engine is not the only thing that powers the vehicle. The transmission system is equally important, and any problem with the transmission system can leave you stuck in the middle of the road. If you notice early symptoms of the P0740 code, it is advisable to follow the above guidelines and diagnose the problem or take your car to a car specialist. If the code persists and is not heeded, the transmission system may fail and also damage the engine. For this reason, the P0740 code should be dealt with as soon as possible.
How to Avoid the P0740 Code?
If the P0740 code is ignored for a long period of time, it can cause serious problems with the driving performance and damage other components in addition to the gearbox. You can avoid this problem by checking and replacing the transmission oil and filter regularly (or at regular intervals). This will ensure that the components inside the transmission system remain well lubricated and operate at maximum efficiency.
If you have any further questions about the P0740 code, simply contact us via the comments below and I will contact you as soon as possible.
Hello I’m Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I’m specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I’m here to give you answers to all your automotive questions and I hope that you enjoy our content.