AutoCodes – Mazda – P0742 Mazda

P0742 Mazda Code - Torque Converter Clutch Circuit Stuck On

Quick Answer

The Torque Converter Clutch (TCC) solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty torque converter clutch solenoid valve. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0742 Mazda indicates Torque Converter Clutch Circuit Stuck On.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty torque converter clutch solenoid valve.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 16,998

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0742 Mazda Description

The Torque Converter Clutch (TCC) solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.
Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

OBDII Code P0742 Mazda - Torque Converter Clutch Circuit Stuck On - AutoCodes.com — P0742 Mazda Code - Torque Converter Clutch Circuit Stuck On

What does this mean?

What are the Possible Causes of the DTC P0742 Mazda?

Low transmission fluid level
Dirty transmission fluid
Faulty torque converter clutch solenoid valve
Torque converter clutch solenoid valve harness or connectors
Torque converter clutch solenoid valve circuit is open or shorted
Transmission internal mechanical problem

How to Fix the DTC P0742 Mazda?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

When the a transmission solenoid is stuck on, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommend changing the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure and that the transmission will need to be rebuilt or replaced.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0742 Mazda code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0742 Mazda Code

1. What are the common symptoms of OBDII code P0742 in a Mazda related to the Torque Converter Clutch Circuit being stuck on?

- Common symptoms include engine stalling at idle, poor fuel efficiency, harsh shifting, and the engine overheating.

2. What are the possible causes of OBDII code P0742 in a Mazda?

- The code P0742 can be caused by issues such as a faulty torque converter clutch solenoid, a malfunctioning torque converter clutch circuit, low transmission fluid level, or a defective transmission control module.

3. How serious is the OBDII code P0742 in a Mazda, indicating the Torque Converter Clutch Circuit is stuck on?

- Ignoring code P0742 can lead to further damage to the transmission system, potentially resulting in costly repairs if left unresolved.

4. Can I continue driving my Mazda with OBDII code P0742 triggered?

- It is not recommended to continue driving your Mazda with code P0742 as it can lead to reduced fuel efficiency, transmission overheating, and potential long-term damage to the transmission system.

5. How can I diagnose and repair OBDII code P0742 in my Mazda at home?

- Diagnosis involves checking the torque converter clutch solenoid, inspecting the wiring for any faults, and ensuring proper transmission fluid levels. Repair may involve replacing the solenoid, repairing the wiring, or reprogramming the transmission control module.

6. Is it possible to clear OBDII code P0742 in a Mazda without fixing the underlying issue?

- Clearing the code without addressing the root cause will only temporarily turn off the check engine light, but the problem will persist and likely trigger the code again in the future.

7. Can a mechanic fix OBDII code P0742 in a Mazda, or does it require a specialist?

- A qualified mechanic with experience in transmission systems should be able to diagnose and repair OBDII code P0742 in a Mazda, but consulting a specialist may be beneficial for complex cases.

8. How much does it typically cost to repair OBDII code P0742 in a Mazda?

- The cost of repairing OBDII code P0742 can vary depending on the underlying issue, parts needed, and labor costs, but it can range from a few hundred to over a thousand dollars.

9. Are there any preventative maintenance tips to avoid triggering OBDII code P0742 in a Mazda?

- Regularly servicing the transmission, checking for leaks, and ensuring proper fluid levels can help prevent issues that may trigger code P0742 related to the Torque Converter Clutch Circuit.

10. Can extreme weather conditions affect the likelihood of OBDII code P0742 appearing in a Mazda?

- Extreme temperatures can potentially exacerbate existing issues related to the torque converter clutch, leading to the triggering of code P0742 in a Mazda.