Restore Your Vehicle’s Core Performance and Reliability
Is your Cadillac STS, Corvette, or Hummer H3 experiencing frustrating issues like a persistent Check Engine Light, sudden stalling, poor fuel economy, or a complete no-start condition? These are classic signs that the brain of your engine—the Engine Control Module (ECM)—is failing. In my 20+ years of hands-on diagnostics, I’ve seen how a faulty ECM can cause a cascade of problems that seem unrelated, making diagnosis a headache for both DIYers and professional technicians. This isn’t just a part; it’s the central command center for your vehicle’s performance, and getting it right is critical.
This is a direct-fit replacement Engine Control Module, part number 12628911. The most significant benefit we offer is our professional programming service. Before this module ships, we will flash it with the very latest GM-certified software updates, specifically matched to your vehicle using the VIN you provide. This critical step ensures seamless integration and optimal performance, eliminating the need for an expensive trip to the dealership for programming. You receive a part that is truly ready for installation right out of the box, restoring the precise fuel delivery, ignition timing, and transmission shifting your vehicle was designed for.
A Technician’s Notebook: The Intermittent Gremlin
I remember a 2009 Cadillac STS that came into my bay with an issue that was driving the owner crazy. It would randomly fail to start, but only after it was warm. Other times, the traction control light would flash for no reason. There were no consistent trouble codes, just a few random communication errors (U-codes) stored in history. After verifying all power and ground circuits to the ECM were solid—a crucial first step—I connected a scope. I found that the ECM’s internal processor was intermittently dropping communication on the CAN bus network when it heated up. We replaced it with a VIN-programmed module like this one. The car started perfectly every time, and all the random electrical gremlins vanished. It’s a perfect example of how a failing 2009-2010 STS Engine Module can manifest in bizarre ways beyond a simple Check Engine Light.
Is Your Vehicle Showing These Signs of ECM Failure?
- ✔ Persistent Check Engine Light (CEL) that won’t clear.
- ✔ Stored diagnostic trouble codes (DTCs) like P0601, P0606, or other internal processor faults.
- ✔ Complete no-start or intermittent starting problems.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Engine stalling, sputtering, or running rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to communicate with a diagnostic scan tool.
A Straightforward Guide to Installation
Replacing the 2009-2010 STS Engine Module is a manageable job for a confident DIYer. For the Cadillac STS, the ECM is typically located on the driver’s side (LH) frame rail. Always consult a service manual for your specific vehicle’s location.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for the system capacitors to discharge.
- Locate the Module: Find the existing ECM on your vehicle. It’s a metal box with large electrical connectors.
- Disconnect Connectors: Carefully disengage the locking tabs on the wiring harness connectors and pull them straight out. Never force them. Inspect the pins for any corrosion or damage.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Mount your new, pre-programmed module in place and securely fasten it.
- Reconnect and Secure: Plug the wiring harnesses back into the new ECM until they click, and ensure the locking tabs are fully engaged. Reconnect the negative battery terminal.
- Final Steps: In some GM vehicles, a security relearn procedure (often called a Passlock or Passkey relearn) may be required. This can typically be done without special tools by cycling the key in the ignition. Your vehicle’s service manual will have the specific steps if needed.
Guaranteed Fitment for Your Vehicle
This module is a direct replacement for service number 12628911 and is also interchangeable with numbers 12636659, 12639300, 1263605, 12628993, 12625453, 12622175, 12630464, and 12678512. It is confirmed to fit the following General Motors vehicles:
- Buick Lucerne: 2009-2011 (4.6L)
- Cadillac CTS: 2009 (6.2L)
- Cadillac DTS: 2009-2011
- Cadillac SRX: 2009 (4.6L)
- Cadillac STS: 2009 (4.4L, 4.6L), 2010 (4.6L)
- Cadillac XLR: 2009
- Chevrolet Colorado: 2009-2012 (2.9L, 3.7L)
- Chevrolet Corvette: 2009 (ZR1)
- Chevrolet Trailblazer: 2009 (6.0L)
- GMC Canyon: 2009-2012 (2.9L, 3.7L)
- GMC Envoy: 2009 (5.3L)
- Hummer H3: 2009-2010 (3.7L)
- Saab 9-7x: 2009
A properly functioning 2009-2010 STS Engine Module is essential for your vehicle’s health. Don’t let a faulty computer keep you off the road. Provide your VIN at checkout and let us send you a reliable, ready-to-install solution.
Frequently Asked Questions
Why do you need my VIN number?
Your Vehicle Identification Number (VIN) allows us to access the exact factory specifications for your car. We use it to load the correct GM software and calibrations for your specific engine, transmission, and options, ensuring perfect compatibility and performance.
Is this part difficult to install myself?
For most DIYers with basic tools, this is a straightforward replacement. It involves disconnecting the battery, unplugging the old module, and bolting the new one in. The key is that our pre-programming service eliminates the most difficult step: the need for dealership-level software tools.
Will I need to do anything after installing it?
In many cases, it’s a simple plug-and-play process. However, some GM vehicles may require a security relearn procedure to sync the new ECM with your anti-theft system. This procedure can usually be done at home by cycling the ignition key and does not require a scan tool.
What is the difference between an ECM, ECU, and PCM?
The terms are often used interchangeably. ECM (Engine Control Module) and ECU (Engine Control Unit) typically refer to the same part. PCM (Powertrain Control Module) is a term for a more integrated unit that controls both the engine and the automatic transmission. For your vehicle, this part serves as the central computer.
Will this fix my failed emissions test?
If the failure was caused by an ECM-related trouble code (like a P0601 or a fuel trim issue), then yes, replacing the faulty module with this correctly programmed one should resolve the issue and allow your vehicle’s emissions monitors to run and pass inspection.