Restore Peak Performance to Your GM Vehicle
Is your 2008-2009 Cadillac CTS, STS, or another compatible GM SUV like the Acadia or Traverse suffering from baffling electrical issues? A faulty Engine Control Module (ECM) is often the culprit behind persistent check engine lights, poor engine performance, stalling, or even a no-start condition. The ECM is the central computer of your vehicle, orchestrating everything from fuel injection and ignition timing to transmission shifting and emissions control. When it fails, it can create a cascade of problems that are difficult to diagnose. This replacement ECM, part number 12628387, is the definitive solution to restore your vehicle’s reliability and drivability.
The Critical Role of a Programmed ECM
Replacing an ECM isn’t as simple as swapping out a mechanical part. Modern vehicles use sophisticated software that is unique to each car’s Vehicle Identification Number (VIN). This programming governs the anti-theft system, engine parameters, and communication with other modules. Our service eliminates the guesswork and the expensive trip to the dealership. We flash this module with the latest official GM software updates, precisely matched to your vehicle’s VIN. This ensures that when you receive the part, it is ready for installation, communicates flawlessly with your vehicle’s systems, and performs exactly as the factory intended.
From the Diagnostic Bay
We once had a 2009 Acadia come in that was a textbook ‘parts cannon’ case. The owner, frustrated with random stalling and a flashing check engine light, had already replaced the crankshaft position sensor, camshaft sensors, and two oxygen sensors based on forum advice. The problems persisted. When we connected our professional scan tool, we noticed intermittent communication loss with the engine module. It wasn’t setting a clear ‘bad ECM’ code, but the data stream was erratic. We installed a VIN-programmed ECM, and every single issue vanished. The owner had spent nearly $600 on unnecessary sensors when the root cause was the vehicle’s computer all along. This highlights the importance of correctly diagnosing a faulty module before replacing other components.
Common Symptoms of a Faulty 2008-2009 CTS ECM
- ✔ Persistent Check Engine Light (CEL) that won’t clear or returns immediately.
- ✔ Unexplained engine stalling, especially when coming to a stop or at idle.
- ✔ Engine misfires, rough idling, or hesitation during acceleration.
- ✔ A complete no-start condition where the engine cranks but will not fire up.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to communicate with OBD-II diagnostic scan tools.
- ✔ Warning lights on the dashboard such as ‘Service StabiliTrak’ or traction control errors.
Guaranteed Compatibility and Simple Installation
This module is a direct replacement for a wide range of GM vehicles equipped with the 3.6L V6 engine. It is compatible with multiple part numbers, including 12623325, 12628387, 12605672, 12630594, and 19300016. The installation process is straightforward for a competent DIY mechanic. The module is typically located in the engine bay (on the right-hand side for the CTS/STS, or behind the fan shroud on the SUVs). After disconnecting the battery, you simply unbolt the old module, disconnect the wiring harnesses, and install the new one. In most cases, the vehicle will start and run perfectly. Some vehicles may require a simple, key-on/key-off security relearn procedure, which takes about 30 minutes and requires no special tools.
Frequently Asked Questions
Is this part truly ‘plug and play’?
Yes, for the vast majority of vehicles. Because we program the module to your specific VIN, it arrives ready to be installed. Some vehicles’ anti-theft systems may require a security relearn procedure, which can be done in your driveway without any special tools. Instructions are readily available online for this simple process.
What information do you need from me after I order?
After you complete your purchase, you will need to provide us with your vehicle’s 17-digit VIN. This is crucial for us to load the correct GM software and ensure perfect compatibility with your car’s specific options and systems.
Do I need to send my old, broken ECM back?
No, there is no core charge or need to return your original module. This is a direct purchase of a replacement part.
Where is the ECM located on my vehicle?
The location varies slightly by model. For the 2008-2009 Cadillac CTS and STS, it’s found in the right-hand (passenger side) front of the engine compartment. For the 2009 Acadia, Traverse, Enclave, and Outlook, it is typically located behind the engine’s cooling fan shroud.
Will this fix my transmission shifting problems?
It can. The ECM works directly with the Transmission Control Module (TCM). If the ECM is failing, it can send incorrect data to the TCM, resulting in poor shifting performance. If your shifting issues are caused by faulty communication from the ECM, this part will resolve them.
My original part number is not on your list, but my vehicle is. Will this work?
GM often supersedes part numbers. The numbers we have listed (12623325, 12628387, 12605672, 12630594, 19300016) are the most common replacements for this application. If you have a different number, please contact us with your VIN and original part number to confirm compatibility before ordering.