Is Your Cadillac STS Running Rough? It Could Be The ECM.
If your 2009-2010 Cadillac STS is experiencing perplexing issues like stalling, poor fuel economy, a persistent check engine light, or a complete no-start condition, the root cause is often a failing Engine Control Module (ECM). As the central computer of your vehicle, the ECM manages everything from fuel injection and ignition timing to transmission shifting. When it begins to fail, it can create a cascade of problems that are difficult to diagnose. This replacement ECM, part number 12628911, is the definitive solution to restore your vehicle’s performance and reliability.
From the Diagnostic Bay
We had a 2009 Cadillac STS come into the shop with a list of intermittent issues that had stumped two other mechanics. The car would randomly misfire, the transmission would shift erratically, and the check engine light would flash with a dozen different codes. The owner had already replaced spark plugs, coils, and even a transmission sensor with no luck. After hooking up our professional scan tool, we noticed the live data stream from the ECM was inconsistent and dropping out. We identified the ECM as the culprit. Instead of a costly trip to the dealer, we installed one of our pre-programmed modules. The car immediately started and ran perfectly smooth. It’s a classic case where chasing symptoms costs more than addressing the root cause—a faulty engine computer.
Symptoms of a Failing 2009-2010 STS Engine Module
A failing engine computer can manifest in various ways. If you’re noticing any of the following, it’s a strong indicator that your ECM needs replacement:
- ✔ Check Engine Light: The light is on or flashes intermittently, often with communication-related error codes (U-codes).
- ✔ Engine Stalling or Misfiring: The engine may stall for no apparent reason, either while driving or at idle. You might also experience rough idling or engine misfires.
- ✔ Poor Performance & Fuel Economy: A noticeable drop in acceleration, power, and a significant increase in fuel consumption are common signs.
- ✔ No-Start Condition: The engine cranks but refuses to start. This can happen if the ECM is not properly controlling the fuel or spark.
- ✔ Transmission Shifting Problems: The ECM works with the Transmission Control Module (TCM), and a fault can lead to harsh shifting, getting stuck in gear, or delayed engagement.
- ✔ Intermittent Electrical Issues: Seemingly unrelated electrical problems can sometimes be traced back to a failing main computer.
A True Plug-and-Play Solution
Don’t waste time and money at the dealership. This module is the ideal solution for your 2009-2010 STS Engine Module replacement. We take the guesswork out of the process. When you place your order, simply provide us with your vehicle’s 17-digit Vehicle Identification Number (VIN). Our technicians will then program the module with the latest, most stable software updates directly from GM. This ensures that the computer is perfectly matched to your vehicle’s specific configuration, including its engine, transmission, and factory options. The result is a simple, plug-and-play installation. In most cases, no further programming is required once the part is installed.
Guaranteed Compatibility
This ECM is a direct replacement for a wide range of General Motors vehicles and is interchangeable with several service numbers. Please verify that your original part number is on this list to ensure a perfect match.
Interchangeable Part Numbers: 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, 12678512
This unit fits a variety of models beyond the Cadillac STS, including the Corvette, Hummer H3, Chevrolet Colorado, GMC Canyon, Buick Lucerne, and more. Please refer to the detailed fitment list to confirm compatibility with your specific vehicle and engine option.
Frequently Asked Questions
Do I need to do any programming after I receive this module?
No. This module comes pre-programmed to your vehicle’s VIN. It is ready for installation right out of the box. In some vehicles, a simple security relearn procedure may be necessary, which can typically be done without special tools.
Where do I provide my VIN?
You can provide your 17-digit VIN during the checkout process. There will be a designated field for you to enter it. Please double-check it for accuracy to ensure correct programming.
What if my original part number is slightly different?
This module is interchangeable with several part numbers listed in the description. As long as your original part number is on our compatibility list, this unit will function correctly in your vehicle.
Is this a new or used part?
This is a high-quality, tested, and verified replacement part that has been programmed with the latest vehicle-specific software. It is guaranteed to restore your vehicle’s functionality.
Will this fix my check engine light?
If the check engine light and associated codes are caused by a faulty ECM, then yes, this part will resolve the issue. It is crucial to have a proper diagnosis to confirm the ECM is the point of failure before ordering.