P0742 Code: Torque Converter Clutch Circuit Stuck On

The torque converter clutch, which creates a mechanical connection between the engine and transmission, is controlled by the powertrain control module (PCM) via a solenoid valve. If the PCM detects a fault within the torque converter clutch circuit, the vehicle’s computer will register a P0742 code on a scan tool.

What Does the P0742 Code Mean?

Diagnostic trouble code P0742 stands for “Torque Converter Clutch Circuit Stuck On.”

The torque converter is typically bolted to a thin metal disc called a flexplate, with a ring gear which interfaces with the starter motor. In order to turn the engine when starting, the ring gear engages the starter motor’s pinion gear.

The clutch inside the torque converter creates a connection between the engine and transmission that increases fuel mileage and lowers transmission fluid temperatures. The transmission control module (TCM) sends a voltage to the torque converter clutch (TCC) solenoid, which sends pressurized fluid to the circuit. If the PCM detects a problem within the circuit causing the TCC solenoid to fail, the PCM will register a P0742 code.

Note: The definition of code P0742 might be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P0742 Code?

• Faulty torque converter clutch solenoid
• Circuit problems, such as a damaged wire or poor connection
• Valve body problems
• Torque converter failure
• Internal transmission failure
• Failed TCM

What are the Common Symptoms of the P0742 Code?

• Illuminated check engine light
• The engine stalls or dies at highway speeds (happens more regularly with GM vehicles)

How to Diagnose the P0742 Code

DTC P0742 is a generic powertrain code that applies to a variety of vehicles with OBD-II. However, specific diagnostic steps can vary depending on the vehicle’s make and model. You’ll have to consult your vehicle’s repair manual to find the right fix for your DTC’s underlying problems. You can use the following video to give you an idea of what the diagnostic process might involve.

If you don’t have sufficient auto repair skills and knowledge, we suggest hiring a professional to inspect your vehicle and run the appropriate tests. A trained mechanic can help you avoid costly DIY mistakes.

How to Fix the P0742 Code

A P0742 code can indicate one or more problems with your vehicle. You’ll have to find the underlying causes of this code to figure out the appropriate fix. Good thing there are plenty of OBD-II resources online to help you diagnose and repair your vehicle. Check out Chilton repair manuals and get ALLDATA’s subscription to get more information on your vehicle and its potential problems.