P0742 Torque Converter Clutch Circuit Stuck On

The P0742 trouble code is an OBD-II diagnostic trouble code associated with the Torque Converter Clutch (TCC) system in an automatic transmission.

P0742 – Torque Converter Clutch Circuit Stuck On

This code means that the Transmission Control Module (TCM) has detected that the Torque Converter Clutch is remaining engaged, or that the system is behaving as though the TCC is stuck in the ON position when it should be released.

The TCC is designed to lock the engine and transmission together under specific driving conditions. When the vehicle slows down or operating conditions require the clutch to release, the TCC must disengage.

If it remains engaged, the engine can be forced to slow down with the transmission as the vehicle approaches a stop. This can cause engine shudder, abnormal RPM behavior and, in some cases, engine stalling.

P0742 can be caused by an electrical problem, a stuck TCC solenoid, a valve-body problem, contaminated transmission fluid, hydraulic pressure problems or a mechanically damaged torque converter.

What Is the Torque Converter Clutch?

An automatic transmission uses a torque converter between the engine and transmission.

The torque converter allows controlled slip so the engine can continue running while the vehicle is stopped and allows smooth power transfer during acceleration.

At cruising speeds, the Torque Converter Clutch (TCC) can engage to create a more direct mechanical connection.

The basic system works like this:

TCM → TCC Solenoid → Hydraulic Pressure → Torque Converter Clutch → Mechanical Lockup

When the TCM commands the TCC OFF, hydraulic pressure should release the clutch.

With P0742, the TCM detects that the clutch appears to remain engaged despite the OFF command or that the TCC circuit is maintaining an ON condition.

What Does "Stuck On" Mean?

"Stuck On" means the TCC is behaving as though it remains engaged when it should have released.

This can happen because:

• The TCC solenoid is stuck

• A valve in the valve body is stuck

• Hydraulic pressure remains applied

• The TCC control circuit is shorted

• The torque converter clutch mechanically sticks

• Transmission fluid contamination prevents proper valve operation

The important point is that P0742 does not necessarily mean the electrical solenoid itself is defective.

The TCM may be commanding the TCC OFF correctly, but a hydraulic or mechanical problem can prevent the clutch from releasing.

Symptoms of P0742

Possible symptoms include:

• Check Engine Light

• Transmission warning light

• Engine stalling when coming to a stop

• Engine shudder

• Harsh deceleration

• RPM dropping unusually low

• Difficulty coming to a smooth stop

• TCC remaining locked at low speeds

• Abnormal transmission operation

• Poor drivability

• Transmission overheating

• Limp mode

The most important symptom to watch for is engine stalling or severe shudder as the vehicle comes to a stop.

What Does P0742 Feel Like While Driving?

Engine shudder when stopping

As the vehicle slows down, the TCC should release. If it remains locked, the engine may feel as though it is being pulled down by the transmission.

RPM drops too quickly

Engine RPM may fall abnormally when approaching a stop.

Engine stalls

In severe cases, the locked torque converter can prevent the engine from continuing to idle as the vehicle stops.

Harsh deceleration

The vehicle may feel as though the transmission is resisting the vehicle more strongly than normal.

Low-speed jerking

The vehicle may jerk or shudder when slowing down.

Abnormal cruising behavior

Depending on the failure mode, the TCC may remain engaged during conditions where it should be released.

Common Causes of P0742

Stuck TCC solenoid

The solenoid may remain hydraulically active.

Shorted TCC control circuit

A short to power or another circuit can cause the solenoid to remain energized.

Sticking valve-body valve

A valve controlling TCC pressure may become stuck.

Contaminated transmission fluid

Debris can interfere with solenoid or valve movement.

Incorrect transmission fluid

Incorrect fluid can affect hydraulic and friction characteristics.

Excessive hydraulic pressure

Incorrect pressure control can prevent the TCC from releasing.

Internal transmission harness problem

The internal wiring may keep the solenoid incorrectly energized.

Damaged TCC solenoid

An internally defective solenoid may not respond correctly to the TCM command.

Worn or damaged valve body

Valve-body wear can cause abnormal TCC hydraulic control.

Torque converter clutch mechanically stuck

The clutch inside the torque converter may fail to release.

TCM fault

A TCM output-driver problem can incorrectly maintain TCC operation, although this is less common.

Is P0742 Serious?

Yes. P0742 can be a serious transmission fault.

A TCC that remains engaged can cause the engine to stall when the vehicle stops.

Continued operation can also increase:

• Transmission stress

• Clutch wear

• Fluid temperature

• Torque converter wear

• Internal transmission damage

If the engine is repeatedly stalling when coming to a stop, the vehicle should not continue to be driven unnecessarily.

Can You Drive With P0742?

Driving with P0742 is not recommended for an extended period.

If the TCC remains locked, the vehicle may operate reasonably well at higher speeds but develop severe problems when slowing down.

Avoid driving if:

• The engine stalls at stops

• The vehicle shudders violently

• The transmission shifts harshly

• The transmission overheats

• The vehicle loses gears

• The transmission enters severe limp mode

If the engine stalls in traffic, there is also an obvious safety concern.

P0742 vs. P0741

P0741 – Torque Converter Clutch Circuit Performance / Stuck Off

The TCC does not achieve the expected lockup or appears stuck OFF.

P0742 – Torque Converter Clutch Circuit Stuck On

The TCC remains engaged when it should release.

These codes describe fundamentally different TCC conditions.

P0742 vs. P0743

P0742 – TCC Circuit Stuck On

The system detects that the TCC remains engaged.

P0743 – TCC Solenoid Circuit Electrical

The system detects an electrical fault in the TCC solenoid circuit.

An electrical problem can cause TCC malfunction, but P0742 specifically concerns the stuck-ON operating condition.

P0742 vs. P0744

P0742 – TCC Circuit Stuck On

The TCC remains engaged when it should disengage.

P0744 – TCC Circuit Intermittent

The TCC circuit or operation becomes abnormal intermittently.

P0742 vs. P0740

P0740 – Torque Converter Clutch Circuit Malfunction

General TCC circuit malfunction.

P0742 – Torque Converter Clutch Circuit Stuck On

The system detects a specific stuck-ON condition.

Where Is the TCC Solenoid?

The location depends on the transmission design.

The TCC solenoid may be:

• Inside the transmission

• Mounted in the valve body

• Located underneath the transmission pan

• Integrated into a solenoid pack

• Part of a mechatronic assembly

Access can therefore vary considerably between vehicles.

How to Diagnose P0742

P0742 requires both electrical and hydraulic diagnosis.

The technician needs to determine whether the TCC is actually being commanded ON or whether it is mechanically/hydraulically remaining engaged despite an OFF command.

1. Scan the TCM

Retrieve all transmission codes.

Check:

• Current codes

• Pending codes

• History codes

• Freeze-frame data

• TCC command

• TCC slip speed

• Transmission temperature

• Engine RPM

• Vehicle speed

• Selected gear

Other codes may point toward the underlying cause.

2. Check the freeze-frame data

Determine exactly when P0742 was detected.

Look at:

• Vehicle speed

• Engine RPM

• Transmission temperature

• Engine load

• Throttle position

• Selected gear

• TCC commanded state

• TCC slip

3. Monitor TCC command

This is one of the most important diagnostic steps.

Determine whether the TCM is actually commanding the TCC ON or OFF.

If the TCM commands OFF but TCC slip remains near zero, the clutch may be mechanically or hydraulically stuck ON.

4. Check TCC slip speed

When the TCC is released, there should normally be converter slip.

If the TCM commands the TCC OFF but slip remains abnormally low, investigate why the clutch remains locked.

5. Check transmission-fluid level

Verify the fluid level according to the manufacturer's procedure.

An incorrect fluid level can affect hydraulic operation.

6. Inspect the transmission fluid

Look for:

• Burnt odor

• Dark or degraded fluid

• Metal particles

• Clutch material

• Excessive contamination

Contamination can cause valves and solenoids to stick.

7. Inspect the transmission connector

Check for:

• Corrosion

• Loose terminals

• Bent pins

• Water intrusion

• Fluid contamination

8. Inspect the TCC wiring

Look for:

• Short circuits

• Damaged insulation

• Chafing

• Melted wiring

• Pinched wires

• Poor previous repairs

A shorted control wire can keep the TCC solenoid energized.

9. Test the TCC solenoid circuit

Check:

• Power supply

• Ground

• Control circuit

• Continuity

• Resistance

• Short to power

• Short to ground

Use the vehicle-specific wiring diagram.

10. Check TCC solenoid resistance

Measure the solenoid according to manufacturer specifications.

An open or shorted coil can indicate a defective solenoid.

However, resistance testing alone cannot determine whether the solenoid is mechanically stuck.

11. Check whether the solenoid responds to commands

If the diagnostic system supports active testing, command the TCC solenoid ON and OFF.

Observe the electrical response and TCC slip.

12. Inspect the valve body

If the TCC remains engaged despite a correct OFF command, inspect the valve body.

Look for:

• Sticking valves

• Restricted passages

• Valve-bore wear

• Hydraulic leakage

• Contamination

13. Check hydraulic pressure

Where the manufacturer provides pressure-testing procedures, measure the appropriate hydraulic pressure.

Incorrect pressure can keep the TCC applied.

14. Evaluate the torque converter

If the electrical and hydraulic systems are functioning correctly but the TCC still does not release, the torque converter itself may have a mechanical problem.

Can a Bad TCC Solenoid Cause P0742?

Yes.

A solenoid that is mechanically stuck or electrically held ON can prevent the TCC from releasing.

Can a Shorted Wire Cause P0742?

Yes.

A shorted control circuit can continuously energize the TCC solenoid.

This is an important distinction from a purely mechanical TCC problem.

Can a Bad Connector Cause P0742?

Yes, although the exact failure mode depends on the circuit design.

A damaged connector can cause incorrect solenoid control.

Can Dirty Transmission Fluid Cause P0742?

Yes.

Contaminated fluid can cause the TCC solenoid or valve-body valve to stick.

Can Low Transmission Fluid Cause P0742?

Low fluid is not the most direct cause of a stuck-ON condition, but incorrect hydraulic operation can contribute to TCC problems.

The fluid level and condition should still be checked.

Can a Bad Valve Body Cause P0742?

Yes.

A sticking TCC valve is a common hydraulic possibility.

The valve can remain in a position that keeps pressure applied to the torque converter clutch.

Can a Bad Torque Converter Cause P0742?

Yes.

A mechanically damaged or stuck TCC inside the torque converter can prevent release.

However, the electrical and hydraulic control system should be tested before condemning the torque converter.

Can a Bad TCM Cause P0742?

Yes, but it is less common.

A failed TCM driver can incorrectly command or maintain the TCC solenoid.

Can P0742 Cause Engine Stalling?

Yes.

This is one of the most important potential symptoms.

If the TCC remains locked as the vehicle comes to a complete stop, the engine may be forced to stop rotating.

This can feel similar to stopping a vehicle with a manual transmission without pressing the clutch pedal.

Can P0742 Cause Shudder?

Yes.

A TCC that does not release correctly can cause significant shudder during deceleration.

Can P0742 Cause Poor Fuel Economy?

It can.

If TCC operation is abnormal, transmission efficiency may decrease.

Can P0742 Cause Transmission Overheating?

Yes, potentially.

Abnormal TCC operation can increase transmission stress and heat.

Can P0742 Damage the Transmission?

Yes.

If the condition is ignored, continued abnormal TCC operation can contribute to:

• Torque converter damage

• Valve-body wear

• Transmission-fluid degradation

• Clutch wear

• Excessive heat

• Internal transmission damage

Common Diagnostic Mistakes With P0742

Replacing the torque converter immediately

The TCC solenoid or valve body may be responsible.

Assuming the TCC solenoid is always the problem

The control circuit may be shorted, or a valve may be mechanically stuck.

Checking only electrical resistance

A solenoid can have normal resistance while being mechanically stuck.

Ignoring TCC command data

The difference between commanded OFF and actual TCC lockup is critical.

Ignoring TCC slip data

TCC slip can help determine whether the clutch is actually remaining locked.

Ignoring the valve body

A sticking valve can keep hydraulic pressure applied to the TCC.

Replacing the TCM too early

The control module should be considered only after the circuit has been properly tested.

What Is the Correct Repair for P0742?

The repair depends on the confirmed cause.

Possible repairs include:

• Repairing a shorted TCC control wire

• Repairing damaged wiring

• Replacing damaged connector terminals

• Cleaning connector corrosion

• Repairing the internal transmission harness

• Replacing the TCC solenoid

• Cleaning a sticking solenoid

• Servicing the valve body

• Replacing a damaged valve

• Cleaning restricted hydraulic passages

• Correcting transmission-fluid level

• Replacing severely contaminated or incorrect fluid

• Repairing hydraulic-pressure problems

• Replacing a defective torque converter

• Updating TCM software where applicable

• Reprogramming the TCM

• Replacing the TCM if its failure is confirmed

How to Test the Vehicle After Repair

After the repair, the TCC system should be tested through the complete operating range.

Verify that:

• The TCM can command the TCC ON

• The TCM can command the TCC OFF

• TCC slip changes appropriately

• The clutch releases when commanded

• Engine RPM does not drop abnormally during stops

• The engine does not stall

• No severe shudder occurs

• Transmission temperature remains normal

• Gear changes are normal

• No additional transmission codes appear

• P0742 does not return

The vehicle should be tested both at cruising speed and during deceleration to a complete stop.

Frequently Asked Questions About P0742

What does P0742 mean?

P0742 means the transmission control system has detected that the Torque Converter Clutch is stuck ON or remains engaged when it should release.

Does P0742 mean the torque converter is bad?

No. The TCC solenoid, wiring, valve body or hydraulic system can also cause the problem.

Can a bad TCC solenoid cause P0742?

Yes.

Can a shorted wire cause P0742?

Yes.

Can a bad valve body cause P0742?

Yes.

Can dirty transmission fluid cause P0742?

Yes.

Can a bad torque converter cause P0742?

Yes, but it should be diagnosed after the electrical and hydraulic systems have been checked.

Can P0742 cause engine stalling?

Yes. A TCC that remains locked can cause the engine to stall as the vehicle comes to a stop.

Can P0742 cause shudder?

Yes.

Can P0742 cause high RPM?

Generally, a stuck-ON TCC is more likely to cause unusually low RPM during deceleration rather than high RPM. Other TCC faults can produce high cruising RPM.

Can P0742 cause overheating?

It can contribute to abnormal transmission operation and heat generation.

Can I drive with P0742?

Driving should be limited, especially if the engine stalls or the vehicle shudders heavily during stops.

Does P0742 mean the transmission needs to be replaced?

No. The problem may be a solenoid, wiring, valve-body or hydraulic fault rather than complete transmission failure.

Final Thoughts on P0742

P0742 – Torque Converter Clutch Circuit Stuck On indicates that the TCC is remaining engaged when the transmission control system expects it to release.

The most important diagnostic question is:

Is the TCM commanding the TCC OFF, but the clutch remains locked?

If yes, the investigation should focus on the TCC solenoid, valve body, hydraulic pressure and torque converter.

If the TCM is incorrectly maintaining the ON command, the technician should investigate the electrical circuit, wiring and TCM control.

A logical diagnostic sequence is:

Scan Tool → TCC Command → TCC Slip → Wiring → Solenoid → Hydraulic Pressure → Valve Body → Torque Converter → TCM

P0742 should not automatically lead to a torque converter replacement. Correctly identifying whether the TCC is being commanded ON or actually stuck ON can dramatically narrow down the diagnosis and prevent unnecessary transmission repairs.