P0740 — Torque converter clutch circuit malfunction

What this code generally means, its most common causes, and how serious it is.

TYPE: GENERICSYSTEM: TRANSMISSION

What does the code P0740 mean?

On an automatic transmission, the torque converter clutch locks up at certain speeds to improve efficiency (less slip, better fuel economy). This code flags a problem in the circuit that controls that lockup.

Common possible causes

A failing torque converter clutch solenoid — the most common cause.
Low or contaminated transmission fluid — affects the pressure needed for lockup.
Damaged wiring or connector — to the relevant solenoid.
Internal torque converter wear — less common, but costlier to fix.

General severity

Moderate to serious — worth a prompt check

This code can show up as shuddering at cruising speed, higher fuel use, or a harsh engagement. Usually still drivable short-term, but worth checking fairly soon to avoid prematurely wearing other transmission parts.

This is still a general severity for this code, not a diagnostic for your car. Only a real read of your codes, with your mileage and vehicle history, can tell what's really going on.

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Meca doesn't replace an in-person check by a professional. For any serious sign (a flashing light, a major loss of power, a fuel smell), see a mechanic promptly.

Frequently asked questions

My car shudders at cruising speed — is that related?

That's a classic symptom of this code — a torque converter clutch that slips or engages poorly can cause shuddering, especially felt on the highway.

Is this related to the transmission fluid?

It can be — low or degraded fluid affects the pressure needed to properly lock the clutch.

My fuel economy went up — is this the cause?

That's a possible symptom, since this clutch exists specifically to improve efficiency — a malfunction can reduce that gain.