When an ECU detects a P0740 DTC, it indicates a problem with the solenoid controlling the torque converter clutch. Therefore, a torque converter clutch (TCC) circuit malfunction causes trouble code P0740 to appear.
No matter what make or model a vehicle is, this generic trouble code may be returned. Nevertheless, repair and diagnosis steps may differ between models.
In a torque converter clutch (TCC), the torque converter control module (TCM) is responsible for controlling the clutch. TCCs lock converter shells to turbine shafts when they are disengaged.
By doing so, the transmission and engine are connected one-to-one to prevent slippage. In addition, whenever the clutch is applied abnormally (more than once), trouble code P0470 is displayed.
P0740 Honda Code Definition: Torque Converter Clutch Circuit Malfunction
This error code indicates a malfunction in the torque converter clutch circuit. This code indicates that the torque converter clutch circuit has detected something unusual, according to the powertrain control module (PCM).
The torque converter clutch can be varied by the powertrain control module for optimal vehicle performance. The powertrain control module will illuminate the Check Engine Light if the torque converter clutch is applied abnormally (usually multiple times).
Honda P0740 Symptoms
There is a wide range of symptoms associated with P0740. It can be a nuisance if the converter remains unlocked. The lock should not be locked when it shouldn’t be. Here’s where it gets dicey. Some of the most common symptoms are:
Higher RPM On Highway
In highway driving, an unlocked converter can cause higher RPMs. Increased fuel mileage and higher transmission temperatures are the results of this practice.
Stutters and Stalls
It is a sign that the transmission is locked during normal operation. Manual transmissions feel precisely the same when downshifting.
Poor Gas Mileage
RPMs will stay higher if the converter doesn’t lock at speed. As a result, fuel mileage decreases.
Some other potential symptoms of the P0740 code may include the following:
- There is a possibility that the transmission will overheat
- The torque converter clutch can fail to engage or disengage, resulting in the vehicle not moving
- It is possible that the transmission shifts harshly
- It is not possible to shift into or out of a certain gear on the transmission
What Are The Causes Of The P0740 Honda Code?
It is possible to receive the P0740 error code for various reasons. In most cases, a professional will be required to diagnose them. This list is presented first based on a combination of the likelihood of causing the issue and repairability.
Transmission Fluid
Transmissions cannot function normally if there is not enough transmission fluid. A low transmission fluid level can cause a number of symptoms. First, there will be a noticeable slip in the transmission.
P0740 codes are thrown when the transmission fluid is dirty or burnt, which can cause the transmission to behave abnormally. It’s pretty easy to determine the color of transmission fluid by looking at this guide.
Fluid replacement should be considered an urgent priority if the level is low or if it’s bad. Fluids and filters for transmissions are relatively inexpensive.
Problem In The Transmission Case
There may be a problem with the transmission case itself if the TCC appears to be working properly. For example, the problem could be caused by a clogged filter, a problem with the valve body, or a pressure problem within the transmission.
Torque Converter
It is possible for the torque converter to go bad or for the torque converter clutch to go bad and throw the P0740 error code.
TCC Solenoid
In most cases, the torque converter clutch solenoid (TCC) has failed. However, if you jump straight to this conclusion without checking the transmission fluid and wiring, you risk causing yourself many headaches.
Wiring Issues
In a vehicle, the wiring harness that connects the transmission to the rest of the engine is one of the most vulnerable components. Therefore, you can diagnose your Honda by inspecting the harness, checking the transmission connection, and finally performing a continuity test.
How To Diagnose The P0740 Honda Code?
A mechanic should first look at the transmission fluid to determine what’s causing the DTC, as dirty fluid can mess up the TCC solenoid.
Damage and corrosion should also be checked on the wiring and connectors. Finally, the torque converter and TCC solenoid must be tested if no issues are found at this stage.
How Does A Mechanic Diagnose The P0740 Code?
Checking the transmission fluid level and condition may be the first step in diagnosing a P0740 code. However, the problem could be caused by anything out of the ordinary.
It is then the mechanic’s responsibility to look up a diagnostic procedure for this code given by the manufacturer in the service information if there is nothing wrong with the transmission fluid. Following the instructions is the next step. The transmission may have to be disassembled or removed for this diagnostic.
Common Mistakes When Diagnosing The P0740 Code
Using the trouble code as a reason to assume that the torque converter is damaged is an easy mistake to make. There can be a lot of money spent on having it replaced when it may just need to be topped off with fluid.
When solving a problem, it is essential to take into account all aspects of it to arrive at the most effective and efficient solution.
What Repairs Will Fix the P0740 Code?
The P0740 trouble code can be addressed by several repairs, including:
- A torque converter or clutch needs to be replaced
- The solenoid in torque converter clutches needs to be replaced
- Replacement of the powertrain control module
- Filters and fluids should be changed or added to transmissions
- Removing the old transmission and installing the new one
- Transform the transmission by performing an overhaul
How Serious Is The P0740 Code?
It can cause drivability issues if the P0740 code is present. Drivers can be left stranded on the side of the road by this code.
When the engine cannot transfer power to the wheels, a well-working transmission is worthless. Diagnosing and repairing this issue as soon as possible is a good idea.
Your transmission fluid and filter (if applicable) should be changed at the recommended intervals to prevent trouble codes such as the P0740 code.
In this way, the transmission’s internal parts will remain well lubricated, and debris will not cause a restriction.
Tech Notes
It is possible that the P0740 code on some Honda vehicles is caused by an overheating torque converter, which is caused by insufficient flow to the torque converter release circuit.
Overheating transmission fluid and more serious transmission problems can result from extended driving with this problem.
Flushing and replacing the transmission is a good start, but sensor and solenoid circuit checks should also be performed.
There is a chance that any of these could be faulty rather than a more expensive reason for the problem.
With Honda Odysseys, however, the problem is often the transmission itself, which must be replaced.
The warranty is extended to cover powertrain issues such as this if the vehicle has exceeded its 100,000-mile warranty. Unfortunately, there is a good chance the owner will have to replace the transmission for several thousand dollars.
Final Words
I’ll give you a quick recap. First, there are several transmission trouble codes, but P0740 is one of the most common ones. Basically, it means that the Honda computer has determined that a fault has been detected in the torque converter clutch (TCC) solenoid circuit.
This allows a true mechanical connection between the transmission and engine due to the TCC “locking” the drivetrain. At certain speeds and engine loads, this enables automatic transmissions to behave like manual transmissions and eliminate slipping.
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