Terraza Power Loss + CEL: ECM Diagnosis Needed

Having dealt with similar symptoms on my 2009 Buick Enclave, I can relate to this power loss issue. The reduced engine performance and check engine light pointed to ECU problems in my case. The main relay was failing intermittently, causing communication issues between the engine control unit and various sensors. A thorough diagnostic scan revealed multiple fault codes related to the control system. The repair involved replacing the main relay and reprogramming the ECU. This was indeed a serious issue that required specialized automotive electronics knowledge to properly diagnose and fix. The symptoms you describe match what I experienced, inconsistent power delivery and engine performance issues. These problems typically worsen over time if left unaddressed. While the initial diagnosis might seem questionable, electronic control system issues can be complex and often require specific testing procedures. For proper diagnosis, look for shops that specifically list experience with automotive electronics and ECU repair. Ask if they have up-to-date diagnostic equipment for GM vehicles and certified technicians familiar with engine control systems. Most independent shops with ASE-certified technicians who specialize in electrical diagnosis should be capable of properly diagnosing and repairing these issues.

Thanks for the detailed response about the ECU problems. I fixed a similar issue on my Terraza when the engine performance suddenly dropped. The computer module was sending incorrect signals, causing the power loss. After getting it diagnosed and repaired at a specialized shop, it has been running great for the past 8 months. How much did the ECU repair and programming end up costing you? Also, have you experienced any other electrical issues since the fix?

Having resolved the engine control unit issues on my Buick, I can confirm the repair was successful and cost-effective. The final bill came to 120 for fixing the defective main relay, which was causing the communication problems in the control system. Since getting the car diagnostics and repair done, the vehicle has been running perfectly with no electrical problems whatsoever. The power is back to normal, and the engine control functions are working as they should. It was definitely worth getting it fixed by a shop that specializes in vehicle electronics. The system reset and reprogramming after the relay replacement really made a difference, no more check engine lights or performance issues. When dealing with car electronics like this, going to the right specialist can save both time and money in the long run. Its great to hear your Terraza is also running well after the repairs. These control system issues can be tricky to diagnose, but once properly fixed, they typically stay resolved.

Thanks everyone for the helpful feedback. After my initial post, I took my Terraza to a certified shop specializing in automotive electronics and engine control systems. The technician found multiple sensor issues affecting the ECU communication. The diagnostic scan revealed faulty wiring connections and a degraded control module. The repair cost came to around 450 Euro including parts and labor for the engine control unit work. The shop had to replace some corroded wiring and reprogram the ECU. Since the fix, the engine performance has returned to normal and the check engine light has stayed off. What really impressed me was how thorough their diagnostic process was compared to the previous shop. They took the time to properly test the vehicle electronics and identify the root cause rather than just guessing. Been driving it for 3 weeks now with no issues, the power is back and it runs great. Just wanted to update everyone and confirm getting it fixed at a shop with proper ECU repair experience made all the difference. Their expertise in engine diagnostics was worth the investment.