Experiencing a rough ride with your car? You might be dealing with the P0742 error code, a common issue indicating a problem with your vehicle’s torque converter clutch (TCC) solenoid. This article, brought to you by the auto repair experts at obd-de.com, will break down the P0742 code, its symptoms, and how to address it, drawing on real-world experiences to guide you toward a solution.
Understanding the P0742 Code: Torque Converter Clutch Stuck On
The P0742 diagnostic trouble code signals “Torque Converter Clutch Circuit Stuck On.” In simpler terms, it means the torque converter clutch solenoid, which is responsible for engaging and disengaging the torque converter clutch, is stuck in the “on” position. This malfunction can lead to a series of noticeable driving issues.
Common Symptoms of a P0742 Code
When the P0742 code appears, you’ll likely notice some distinct symptoms while driving. These can include:
- Harsh 1-2 Shifting: The gear change from first to second gear may feel abrupt and jarring.
- Transmission Slipping at Highway Speeds: You might experience a sensation of the transmission losing grip or failing to properly transfer power, especially at higher speeds.
- Vehicle Shudder and Stalling at Stops: As you come to a complete stop, the car may shake or shudder, and in some cases, the engine might shut off, mimicking the stall of a manual transmission vehicle.
- P0700 Code: Often, the P0742 code is accompanied by the P0700 code, which is a general indicator that your transmission control system needs servicing.
These symptoms arise because the torque converter clutch solenoid, when stuck on, is constantly applying the clutch. This disrupts the normal operation of the transmission, particularly during gear shifts and when idling at a stop.
The Root Cause of P0742 in Certain GM Vehicles
For owners of specific General Motors vehicles, particularly the 2013 Buick Enclave, there’s a known issue related to the Transmission Electro-Hydraulic Control Module (TEHCM) and the TCC solenoid. Older GM models with first-generation TEHCMs were prone to problems with wafer disks in pressure sensors. However, the 2013 Enclave, among other models, utilizes a second-generation TEHCM, which eliminates these wafer disks and uses computer learning for pressure adaptation.
Despite this improvement, the TCC solenoid itself can still malfunction. As one user discovered, even without the problematic wafer disks, a P0742 code can appear due to solenoid issues within the TEHCM. Initially, replacing the transmission fluid might offer temporary relief, potentially improving drivability and mitigating the stalling issue by manually shifting into neutral before stopping. However, this is not a permanent fix.
The Solution: GM Technical Service Bulletin (TSB) 13120C
Instead of immediately opting for a costly TEHCM replacement, which dealerships might suggest, there’s a more economical approach. General Motors issued a Technical Service Bulletin, specifically TSB 13120C, addressing this exact problem. This bulletin outlines a procedure involving a solenoid cleaning process that can be performed using a GM dealer’s diagnostic computer.
This cleaning process aims to resolve issues with the TCC solenoid without requiring a complete TEHCM replacement. One user reported success by requesting their dealer to perform the TSB 13120C procedure and the solenoid cleaning. The result was a significant cost saving, with a charge of only $140 for labor compared to a potential $1400 for a TEHCM replacement.
It’s crucial to note that the effectiveness of TSB 13120C and solenoid cleaning might depend on addressing the issue relatively soon after the initial symptoms appear and could be year-specific, as highlighted for the 2013 models.
Conclusion: Try TSB 13120C Before TEHCM Replacement for P0742
If you’re facing a P0742 error code, especially with a 2013 Buick Enclave or similar GM vehicle exhibiting the described symptoms, consider requesting your dealer to investigate and perform the service outlined in GM TSB 13120C before agreeing to a full TEHCM replacement. This proactive step could save you significant money and resolve your transmission issues effectively. Always ensure to consult with a certified mechanic to properly diagnose and address any automotive problems.
