Damaged transmission wiring harness, loose connection, or open or shorted circuit (OBD-Codes.com). Faulty torque converter clutch (lockup) solenoid (both sources). Faulty transmission control module (OBD-Codes.com). Defective torque converter clutch (RepairPal). Defective valve body (RepairPal). Dirty transmission fluid restricting the hydraulic passages (RepairPal). Defective engine coolant temperature sensor, since the clutch only locks once the engine is warm (RepairPal).

Repair damaged wiring or connectors in the TCC circuit (OBD-Codes.com). Replace the torque converter clutch solenoid, which on some models comes as one unit with the internal transmission harness (OBD-Codes.com). Service dirty transmission fluid (RepairPal). Replace a faulty engine coolant temperature sensor (RepairPal). Repair the valve body or torque converter clutch (RepairPal). Replace the transmission control module only after wiring and solenoid check out (OBD-Codes.com).

P0740🔧 Transmission / Torque converter clutchDrive with caution, fix soon

P0740: Torque Converter Clutch Circuit Malfunction (Meaning, Causes, Fixes)

Q: What does P0740 mean?

P0740 means the transmission or engine computer has detected a problem with the torque converter clutch (TCC), the clutch that locks the engine and transmission together at cruising speed to save fuel. OBD-Codes.com points to the electrical side (wiring, the TCC solenoid or the transmission control module), while RepairPal also lists a worn torque converter clutch, the valve body, dirty transmission fluid and a bad engine coolant temperature sensor. Automatic transmissions use a torque converter, a fluid coupling between the engine and transmission. At steady road speed, the computer energizes a torque converter clutch (TCC) solenoid on the transmission valve body, which sends hydraulic pressure to lock the converter so the engine and transmission turn at a 1 to 1 ratio. That cuts slippage, fuel use and emissions. OBD-Codes.com (Dan Weller, ASE Certified Master Technician) describes P0740 as the transmission control module detecting a fault in the circuit that operates the TCC solenoid; on some vehicles the PCM/ECM controls it instead. RepairPal names it Torque Converter Clutch Circuit/Open and says the code sets when the computer sees more than a 200 RPM difference between the torque converter and the transmission input shaft when the clutch should be locked. RepairPal adds that the lockup clutch is applied only when the proper road speed and engine temperature are reached. Similar codes include P0741 through P0744, P2769 and P2770. OBD-Codes.com says that if other transmission codes appear with P0740, an electrical failure is likely.

Q: Can I keep driving with P0740?

Drive with caution, fix soon. Get it checked soon. The two sources disagree on how serious it is: RepairPal rates P0740 Urgent, meaning it can cause severe damage or be unsafe, and says that in some cases the car may stall when coming to a stop after freeway driving or act like it's misfiring. OBD-Codes.com lists only the check engine light and a minimal drop in fuel economy and says it will not affect engine performance. If the engine stalls when you stop, or other transmission codes show up with it, don't put off the diagnosis. An open code can also fail an OBD2 emissions inspection.

Reviewed 2026-10-22 · Based on 2 cited source(s)

What P0740 means

Automatic transmissions use a torque converter, a fluid coupling between the engine and transmission. At steady road speed, the computer energizes a torque converter clutch (TCC) solenoid on the transmission valve body, which sends hydraulic pressure to lock the converter so the engine and transmission turn at a 1 to 1 ratio. That cuts slippage, fuel use and emissions. OBD-Codes.com (Dan Weller, ASE Certified Master Technician) describes P0740 as the transmission control module detecting a fault in the circuit that operates the TCC solenoid; on some vehicles the PCM/ECM controls it instead. RepairPal names it Torque Converter Clutch Circuit/Open and says the code sets when the computer sees more than a 200 RPM difference between the torque converter and the transmission input shaft when the clutch should be locked. RepairPal adds that the lockup clutch is applied only when the proper road speed and engine temperature are reached. Similar codes include P0741 through P0744, P2769 and P2770. OBD-Codes.com says that if other transmission codes appear with P0740, an electrical failure is likely.

Severity: can I keep driving?

Drive with caution, fix soon

Get it checked soon. The two sources disagree on how serious it is: RepairPal rates P0740 Urgent, meaning it can cause severe damage or be unsafe, and says that in some cases the car may stall when coming to a stop after freeway driving or act like it's misfiring. OBD-Codes.com lists only the check engine light and a minimal drop in fuel economy and says it will not affect engine performance. If the engine stalls when you stop, or other transmission codes show up with it, don't put off the diagnosis. An open code can also fail an OBD2 emissions inspection.

Common symptoms

Check engine light on (both sources)
Decrease in fuel economy (both sources; OBD-Codes.com calls it minimal)
Vehicle won't shift into the highest gear at freeway speed (RepairPal)
In some cases, stalling when coming to a stop after freeway driving or misfire-like symptoms (RepairPal)
In unusual cases, nothing the driver notices (RepairPal)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Damaged transmission wiring harness, loose connection, or open or shorted circuit (OBD-Codes.com)
Faulty torque converter clutch (lockup) solenoid (both sources)
Faulty transmission control module (OBD-Codes.com)
Defective torque converter clutch (RepairPal)
Defective valve body (RepairPal)
Dirty transmission fluid restricting the hydraulic passages (RepairPal)
Defective engine coolant temperature sensor, since the clutch only locks once the engine is warm (RepairPal)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Write down every code stored with P0740. Other transmission codes alongside it point toward an electrical problem, per OBD-Codes.com.
Check the transmission fluid level and condition; RepairPal lists dirty fluid restricting the hydraulic passages as a cause.
Check the transmission wiring harness and connectors for damage, corrosion or loose plugs, and check related fuses or relays.
With a multimeter and a factory wiring diagram, OBD-Codes.com describes checking the TCC solenoid circuit resistance at the transmission connector (very high or OL suggests a bad internal harness or solenoid), checking for shorts to ground, and checking for battery voltage on the power side with key on, engine off.
Confirming the computer is actually commanding the solenoid needs an advanced scan tool and a graphing meter or oscilloscope, per OBD-Codes.com; that part is usually a shop job.

Typical fixes

Repair damaged wiring or connectors in the TCC circuit (OBD-Codes.com)
Replace the torque converter clutch solenoid, which on some models comes as one unit with the internal transmission harness (OBD-Codes.com)
Service dirty transmission fluid (RepairPal)
Replace a faulty engine coolant temperature sensor (RepairPal)
Repair the valve body or torque converter clutch (RepairPal)
Replace the transmission control module only after wiring and solenoid check out (OBD-Codes.com)

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

The car stalls when coming to a stop or acts like it's misfiring; RepairPal rates P0740 Urgent
Other transmission codes are stored with P0740
Testing needs the transmission pan removed or an advanced scan tool and oscilloscope
RepairPal warns that P0740 is commonly misdiagnosed as an engine misfire, an internal transmission problem or a driveline problem

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0740 serious?

The sources disagree. RepairPal rates it Urgent and says some cars stall when coming to a stop after freeway driving. OBD-Codes.com says the main effect is a minimal drop in fuel economy and that engine performance isn't affected. Have it checked soon, and sooner if the car stalls or other transmission codes appear.

What is the difference between P0740 and P0741?

Both concern the torque converter clutch. OBD-Codes.com and RepairPal describe P0740 as a fault in the TCC circuit (Circuit/Open), while RepairPal names P0741 Circuit Performance/Stuck Off, meaning the clutch isn't locking as expected.

Can a coolant temperature sensor cause P0740?

RepairPal lists a defective engine coolant temperature sensor as a common cause, because the lockup clutch is applied only once the proper engine temperature is reached.

Can I fix P0740 myself?

Some checks are DIY: fluid condition, wiring, connectors and fuses. OBD-Codes.com's solenoid and computer tests need a wiring diagram, a multimeter and, to confirm the computer's command, an advanced scan tool and graphing meter. Solenoid replacement often means removing the transmission pan.

Why do the sources disagree?

RepairPal rates P0740 Urgent and lists stalling, misfire-like symptoms and no top gear at freeway speed; OBD-Codes.com lists only the check engine light and minimal fuel economy loss. OBD-Codes.com focuses on electrical causes (wiring, solenoid, TCM), while RepairPal adds the torque converter clutch, valve body, dirty fluid and the coolant temperature sensor.

Sources

Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.