P0740 means Torque Converter Clutch Circuit Malfunction. There is an electrical problem in the torque converter clutch (TCC) circuit, so the computer cannot control lockup. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0740 means
Electronically controlled automatics are run by a transmission control module (TCM), a separate box or part of the engine computer. It reads speed sensors, the range sensor and fluid temperature to decide when to shift, and drives solenoids that apply clutches and the torque converter clutch. Many basic code readers only show the generic P0700; a scan tool that reads the transmission module shows the specific fault. Check fluid level and condition first, since low or burnt fluid causes many transmission codes.
P0740 symptoms
- No converter lockup, with higher engine speed at cruise
- Lower fuel economy
- Stalling when stopping if the clutch stays applied
Common causes of P0740
- Failed TCC solenoid
- Wiring or connector damage
- TCM problems
How to diagnose P0740
- Check the TCC solenoid circuit for resistance and shorts
- Inspect the transmission harness and connector
- Check for related solenoid codes
Can you drive with P0740?
Usually drivable, but extra heat from an unlocked converter is hard on the fluid. Repair soon.
P0740 tips
P0740 is an electrical code, so test the solenoid circuit before blaming the converter. An open circuit or failed solenoid usually means the converter never locks, which shows up as slightly higher engine speed at highway cruise.
Will P0740 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0740 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0741 | Torque Converter Clutch Circuit Performance or Stuck Off |
| P0750 | Shift Solenoid A Malfunction |
| P0700 | Transmission Control System Malfunction |
Guides that help
When it is more than a sensor
If the fault turns out to be internal (worn clutches, a failed converter or a damaged valve body), compare a rebuild with a replacement in transmission rebuild vs replacement and transmission replacement cost, identify your unit with what transmission do I have?, and browse our transmissions.
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