P0740

Torque Converter Clutch Solenoid Circuit/Open

Car Fault Codes Transmission

Can you still drive? With care, short trips only

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 5 hours

Typical cost SAR 100 to 2,500

What it means

The transmission control module (TCM) has detected that the circuit of the solenoid that locks the torque converter clutch is open or not responding electrically. The computer usually disables converter lockup, so the car still drives but with higher engine speed on the highway and higher fuel use.

Symptoms5

Engine speed higher than usual when cruising at a steady highway speed.
Noticeably higher fuel consumption.
Check engine light on, sometimes with a transmission warning.
Higher transmission fluid temperature on long trips.
On some vehicles, the transmission enters limp mode for a while.

Possible causes6

Corroded, loose or oil-soaked transmission connector.
Broken or chafed wire in the harness between the computer and the transmission.
Open (burned) coil inside the solenoid itself.
Heat-damaged internal wiring harness inside the transmission.
Failed fuse or relay feeding the solenoid circuit on some designs.
Fault in the driver circuit inside the transmission computer (less common).

How to diagnose6

Read all stored codes; several solenoid codes at once point to a shared power feed or the main connector.
Visually inspect the transmission connector and harness for corrosion, oil or loose pins.
Measure the solenoid coil resistance at the connector and compare it with the manufacturer specification.
Check for power and for continuity of the control wire between the computer and the connector with a multimeter.
Use the scan tool to command the solenoid on, if supported, and watch the circuit status.
If resistance is correct at the connector and the code returns, remove the transmission pan and inspect the internal harness.

How to fix6

Clean and reseat the transmission connector, and replace its seal if fluid is leaking into it.
Repair the broken or chafed wire in the external harness.
Replace the internal harness if it is damaged.
Replace the torque converter clutch solenoid if its resistance is out of specification.
Reprogram or replace the computer only after the wiring and solenoid are ruled out.
Clear the codes, then road test on a highway and confirm lockup returns and the code stays off.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when a connector or external wire is to blame, and rises when the transmission must be opened to replace the solenoid or internal harness, or the computer must be reprogrammed.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

Will the transmission be damaged if I wait?

The fault itself is electrical, but long drives without converter lockup raise fluid temperature, and excess heat shortens transmission life, so repair it soon.

How can I tell the converter is not locking?

Watch the tachometer at a steady highway speed; if the RPM stays higher than usual and never drops slightly after a few seconds of cruising, lockup is probably not happening.

Does the transmission have to be opened?

Not always. Start with the connector and external wiring, where many cases are solved; open the pan only if the fault is proven to be internal.

This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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