P0740 Code Meaning and Next Steps

First checks take 10 to 20 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The transmission slips, bangs into gear, or will not shift correctly.
!The vehicle loses drive, enters limp mode, or the warning light is paired with obvious transmission trouble.

If the light is steady and the vehicle still drives normally: Maybe, but only for a short distance if the transmission still shifts normally.

What to check first

Step-by-step checks

1
Free - no tools
Check the fluid level and condition before replacing the solenoid
2
Free - no tools
Inspect the transmission connector and harness for damage or fluid intrusion
3
Basic tool needed
Notice whether the problem shows up at cruise speed or only after the transmission is warm
4
Basic tool needed
If scan data is available, compare commanded lockup with actual behavior
5
Basic tool needed
If the vehicle has other transmission codes, diagnose them together rather than in isolation

If the code returns

-If the lockup command and actual behavior do not match, the TCC solenoid or circuit becomes more likely.
-If the code returns after a fluid or connector repair, re-check the command side under load.
-If the vehicle is slipping or overheating, do not keep driving it for long before diagnosis.

Background

What this code means

P0740 is a generic OBD-II transmission code for the torque converter clutch circuit.

A TCC circuit fault can come from the clutch solenoid, wiring, or a control issue that prevents lockup from working correctly.

The vehicle may feel like it is not locking up at cruise, or the transmission may run hotter than normal.

Diagnosis

Common causes

Most common

Failed TCC solenoid

The converter clutch may no longer apply or release correctly.

Common

Connector or harness issue

A damaged feed or signal path can break the circuit.

Common

Fluid or pressure issue

Low or incorrect fluid can stop the clutch from working as intended.

Possible

Control-side fault

The transmission controller may not be commanding lockup properly.

Avoid these mistakes

What not to do

xDo not keep driving if the transmission is slipping, flaring, or refusing to shift correctly.
xDo not assume the scan code tells you the exact failed part without checking the fluid, connectors, and symptoms first.

Parts

Parts that may need replacing

PartTypical costNotes

Torque converter clutch solenoid$50-$250Relevant when the circuit and command tests point to the solenoid.

Transmission fluid service$80-$250Important if fluid level or condition is suspect.

Connector or harness repair$20-$120Worth checking if the transmission connector is damaged.

Related OBD codes

P0700

P0700 usually means the transmission control system has a fault stored in the transmission module.

P0730

P0730 usually means the transmission has detected an incorrect gear ratio.

P0750

P0750 usually means shift solenoid A is not behaving correctly.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0740 was expanded around common torque-converter-clutch circuit faults, including solenoid failure, wiring issues, and fluid problems.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0740 - P0740 Usually Means the Torque Converter Clutch Circuit Is Not Behaving Correctly