P0740: Torque Converter Clutch Circuit Malfunction

Your “Check Engine Light” is on and your scan tool throws the P0740 code? 

Read on to have a first evaluation of your situation!

  • P0740 Definition: Torque Converter Clutch Circuit Malfunction.
  • Code type: Generic – P0740 indicates the same problem whether you’re having a Dodge, Honda, or Jeep, etc.          
  • Can I drive with the P0740 code? No, stop driving and have your car fixed immediately.
  • Is it easy to fix? Beginner – advanced level.
  • Cost: $15 – $5,000.

If you don’t want to waste your money and get nothing, let’s dive into six causes that might trigger the P0740 code and the corresponding solutions.

Table Of Contents

What Does The P0740 Code Mean?

The P0740 code activates when the transmission control module (TCM) detects a fault in the clutch solenoid circuit of the torque converter.

Further explanation:

There is a torque converter between the automatic transmission and the engine. Its function is to transfer the power generated from the engine to the transmission input shaft.

Transmission control module or TCM is a vital component running on an automatic transmission system. It is responsible for calculating the right time and place to shift gears for the best driving experience. 

TCM also tells car owners when there is a problem with the transmission by sending specific codes to the vehicle’s main computer.

If the TCM detects a fault within the torque converter clutch circuit, the P0740 trouble code activates. While this is a generic powertrain code applicable to all vehicle types, the specific fix may vary depending on your transmission. It’s essential to check your manual for particular solutions before proceeding with any diagnosis. 

There are several causes that can lead to P0740.

Each has its own solution.

To identify exactly which is the right fix for your car, read the table below. 

P0740 causes, symptoms, and how to fix.

P0740 Causes Identification: Quick View

When diagnosing the P0740 code in your vehicle with a scanner tool, you may have noticed other codes related to this error. 

Codes CombinationCausesSolutions
P0740 onlyFaulty torque converter clutch solenoid

Faulty torque converter

Replace faulty torque converter clutch solenoid

Replace faulty torque converter

P0740 + P0897
Low transmission fluid

Dirty transmission fluid

Add more transmission fluid to the proper level

Change transmission fluid
P0740 + P0700
Faulty transmission

Faulty valve body
Repair, rebuild, or replace faulty transmission

Replace faulty valve body

P0740 + P0115

Faulty engine coolant temperature sensor
Replace faulty ECT sensor

Note: The causes for each code combination are the most common ones. There can be some uncommon issues hidden under those codes.

P0740: Causes, Symptoms, And How To Fix

Cause #1: Faulty Torque Converter Clutch Solenoid 

Torque converter clutch solenoid measures the fluid pressure and regulates how much fluid the lockup takes.

If the solenoid goes bad, there won’t be an accurate measure of how much transmission fluid is needed, leading to abnormal fluid pressures.

Faulty torque converter clutch solenoid symptoms:

  • Increase in fuel consumption.
  • Transmission does not downshift.
  • Erratic shifting with torque converter clutch solenoid.
  • Stuck in neutral or delay in shifting.
  • Fail-safe or limp mode.

Once recognize any of the symptoms listed above, try to have your faulty torque converter clutch solenoid replaced ASAP to prevent further damage.

Cause #2: Faulty Torque Converter

A torque converter is a must-have component in the automatic transmission system. Its function is to act as a hydraulic pump and coupling between the engine and the transmission.

A faulty torque converter is one of the most common transmission problems car drivers normally see, and when it fails, it usually leads to other internal transmission damage. 

Faulty torque converter symptoms:

  • Loss of acceleration.
  • Slipping between gears.
  • Vehicle won’t shift at all.
  • Transmission is overheating.
  • Dirty transmission fluid.

Replacing faulty torque converter is the optimal way to fix the P0740 code if it is the problem.

Cause #3: Low, Dirty Transmission Fluid

Transmission fluid helps lubricate the components of a car’s transmission for the optimum driving experience.

When the transmission fluid level is lower than expected or contaminated, it may damage the whole transmission system, which leads to other problems with the car’s performance.

transmission fluid color chart
When transmission fluid turns into dark brown, it’s time for car drivers to have it changed.

This problem is not a big deal compared to other issues in a car. However, ignoring it can lead to further damages that cost car owners an arm and a leg to get fixed. 

Low/dirty transmission fluid symptoms:

  • P0740 + P0897 code activated.
  • Humming or clunking noise.
  • Shuddering or shaking.
  • Burning smell.
  • Gear slippage.
  • Transmission overheating.
  • Gear shifting problems.

Transmission fluid issue is quite simple to fix for all car owners. Make sure you find the right transmission fluid for your car for the best performance.

This video on how to change transmission fluid from Scotty Kilmer is really straightforward and useful for car drivers. I suggest you to spend a couple of minutes watching this before doing it by yourself.

Cause #4: Faulty Valve Body

A transmission valve body is a maze-like control center directing transmission fluid where it’s needed and helping your vehicle shift gears smoothly.

When there’s a problem in a transmission valve body, it means that the channels which perform the same task as a hydraulic fluid hose can be abraded and oversized, leading the whole valve body to become warped.

Faulty valve body symptoms:

  • P0740 + P0700 code activated.
  • Gear changing problems.
  • Slipping transmission.
  • Banging or knocking sound.
  • Unable to downshift.
  • Check engine light on.

Replacing the faulty valve body with a new one will solve this problem.

Cause #5: Faulty Engine Coolant Temperature Sensor

An engine coolant temperature sensor or ECT sensor takes responsibility to estimate the engine coolant’s temperature.

Some typical faults can arise from coolant temperature sensors over time that can lead to a range of problems developing, including overheating and poor engine performance. 

Faulty engine coolant temperature sensor symptoms:

  • P0740 + P0115 code activated.
  • Poor fuel economy.
  • Irregular temperature readings.
  • Black smoke from the exhaust.
  • Engine overheating.
  • Check engine light on.

A coolant temperature sensor is not too expensive, you can erase this code from your car by replacing the ECT sensor.

Cause #6: Faulty Transmission

Transmission plays a vital role in moving the power from the engine to the wheel. This component helps the gear ratio between the drive wheels and the engine adjust easily as the car slows down or speeds up.

When a car transmission goes wrong, it may trigger car owners’ headaches due to the expensive transmission replacement cost. 

Luckily, replacing is not the only way to resolve transmission problems if you notice earlier symptoms.

Faulty transmission symptoms:

  • P0740 + P0700 code activated.
  • Refusal to switch gears.
  • Burning smell.
  • Slipping gears.
  • Dragging clutch.
  • Leaking transmission fluid.
  • Check engine light.
  • Grinding or shaking.

There are three ways you can use to fix a failing transmission. You can repair, rebuild or even replace for the best result.

How Much Does It Cost To Fix The Code P0740?

Normally, a car owner has to pay around $100 to have the P0740 code fixing job done.

However, bear in mind that the repair cost to fix the code can vary a lot if you choose to fix it yourself or go to a mechanic shop.

The Estimated Repair Cost Of P0740

Torque converter clutch solenoid replacementDIY: $15 - $100
Repair shop: $70 - $200

Torque converter replacementDIY: $150 - $500
Repair shop: $600 - $1,000

Valve body replacementDIY: $200 - $1,000
Repair shop: $400 - $1,500

ECT sensor replacementDIY: $60 - $90
Repair shop: $150 - $200

Transmission repair

DIY: $500 - $2,600
Repair shop: $1,500 - $5,000

Transmission rebuildDIY: $500 - $2,600
Repair shop:$1,500 - $ 3,000
Transmission replacement DIY: $500 - $2,600
Repair shop: $1,800 - $3,400

Note: The data in this table is collected in May 2022. The actual price depends on many factors, such as your car’s make and year, mechanic’s rate, etc. 

You Ask, I Answer

The P0740 code is one of the most severe trouble codes as it leads to transmission-related issues, which is expensive to repair. The sooner you fix the code, the more money you can save from mechanic shops. 

If you have any other questions, don’t hesitate to leave comments below, we’ll answer them all.

If you have had the code and fixed it before, share your story and you’ll help lots of folks having this problem.  

See ya!

Read more: The 9 Best OBD2 Scanners for 2022: The Only Review You Need

2 thoughts on “P0740: Torque Converter Clutch Circuit Malfunction”

  1. Thank you I’ve been trying to pass smog test. The car runs really well but still codes on for P0171 P0174. I noticed a crack in the by pass hose. Could that be a reason? I’m not mechanically inclined I’m a woman thank you

    1. Hi Rhonda,

      Thank you for your question.

      I don’t know why you ended it up in an article about transmission codes asking about engine codes. But yea, vacuum leak is very likely to be your problem. And fixing is not really difficult and expensive.

      I wrote an article talking about lean conditions codes. You can check it out here: https://obdadvisor.com/codes/p0171/

      Let me know if you have any other questions. Good luck!

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