P0740 on Cadillac: How to Diagnose & Fix
Torque Converter Clutch Circuit Malfunction
1 Cadillac model · 1 documented issue · $200-$3,500 repair
P0740 on Cadillac by model: symptoms, diagnosis and fix
The Cadillac XT5 uses an 8-speed (2017-2019) or 9-speed (2020+) automatic transmission. The 8-speed shares the torque converter shudder issue with other GM 8-speed vehicles. The 9-speed (GM 9T50/9T65) can have harsh shifts, delayed engagement, and shift hunting. Both transmissions have been subject to multiple software calibration updates from GM. The 9-speed is particularly sensitive to fluid condition and requires proper Dexron HP fluid.
Common Symptoms
- Shudder at light throttle between 25-50 mph (8-speed)
- Harsh or clunky 1-2 shift
- Delayed engagement from Park to Drive
- Transmission hunting between gears on hills (9-speed)
- Hesitation on acceleration from stop
How to Fix
First step is a TCM software update at the dealer - multiple calibrations have been released. For 8-speed shudder, a fluid exchange with Mobil 1 LV ATF HP may resolve it. The 9-speed typically responds well to software updates. Persistent issues may require torque converter replacement (8-speed) or valve body replacement (9-speed).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- AW-1 Automatic Transmission Fluid (8-speed models, 1 qt)OEM19256039Cross-refACDelco 10-4062 (same fluid, retail number), GM 19256040 (Canada), Idemitsu Type AW-1 / TLS-LV ATF$11–$22
For 2017-2019 XT5, which uses the Aisin AWF8F45 (AF50-8) 8-speed transaxle - NOT the GM 8L45 named in the issue write-up (8L45 is a rear-drive unit and does not fit the transverse XT5). Correction that matters for buyers: Mobil 1 LV ATF …
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Sources for this issue (1)
P0740 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0740 mean on a Cadillac?
P0740 stands for "Torque Converter Clutch Circuit Malfunction." This code indicates a malfunction in the torque converter clutch (TCC) circuit of an automatic transmission. The torque converter clutch mechanically locks the engine to the transmission at cruising speed to improve fuel economy and reduce slippage, and it is engaged by a solenoid controlled by the transmission computer. The code sets when the computer detects an electrical problem with the clutch circuit or sees that the clutch is not engaging or holding as expected. Common signs include slipping, shuddering, poor fuel economy, or stalling when coming to a stop. On Cadillac it is documented across 1 model: XT5.
What are the most common causes of P0740?
The most common causes of P0740 are: Faulty torque converter clutch (TCC) solenoid, Low or contaminated transmission fluid, Wiring or connector fault in the TCC circuit, Worn or failing torque converter, Valve body wear or sticking valves, Internal transmission electrical short, Faulty transmission control module. The specific cause varies by vehicle.
How much does it cost to fix P0740 on a Cadillac?
Published repair estimates on Cadillac range from $200 to $3,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0740 on a different make?
View P0740 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.