Restore Your Truck’s Core Performance and Reliability
If your 2009 Sierra 1500 is suddenly stalling, shifting erratically, or showing a persistent Check Engine Light, the problem often lies with the very brain of your vehicle: the Engine Control Module (ECM). As a technician with over two decades of experience, I’ve seen firsthand how a failing ECM can cause a cascade of frustrating, hard-to-diagnose issues. This isn’t just a part; it’s the central command center for your engine’s performance, fuel efficiency, and emissions. Replacing it shouldn’t be a gamble or require an expensive trip to the dealership for programming.
This is the direct, reliable solution you’ve been searching for. We provide a fully tested Engine Control Module, part number 12625455, that comes pre-programmed to your truck’s specific Vehicle Identification Number (VIN). We flash it with the latest GM-certified software updates, ensuring it communicates flawlessly with your vehicle’s other systems right out of the box. This eliminates the most common hurdle for both DIY mechanics and professional shops, saving you hundreds in programming fees and valuable time.
Case Study: A Tricky Diagnosis
I remember a 2009 Sierra 1500 that came into my bay with a complaint of intermittent stalling at stop lights and a random ‘Service StabiliTrak’ message. The owner had already replaced the throttle body and a few sensors with no luck. The scan tool showed a generic communication code (U0100) that would come and go. After verifying the wiring harness was intact, we zeroed in on the ECM. The internal processor was failing intermittently, especially when hot. Swapping in a pre-programmed 2009 Sierra 1500 Engine Computer like this one solved every single issue instantly. The truck ran smoother than it had in years—a testament to getting the core problem fixed right.
Is Your Vehicle Showing These Symptoms?
A failing ECM can manifest in many ways. If you’re experiencing any of the following, this module is the likely solution:
- ✔ Check Engine Light is on with codes like P0601, P0606 (ECM/PCM Processor Fault) or U0100 (Lost Communication with ECM).
- ✔ Engine cranks but refuses to start.
- ✔ Unexplained drops in fuel economy.
- ✔ Rough idling, stalling, or hesitation during acceleration.
- ✔ Automatic transmission shifting harshly or at the wrong times.
- ✔ Apparent loss of spark or fuel injector pulse.
A Straightforward Guide to Installation
Replacing your ECM is a manageable job for a confident DIYer. Follow these general steps for a successful installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow the system to fully discharge.
- Locate the ECM: On most 2009 Sierra 1500 models, the ECM is located in the engine compartment on the driver’s side, near the firewall or fender.
- Disconnect the Connectors: Carefully unclip the wiring harness connectors from the old module. These connectors have locking tabs; be gentle to avoid breaking them.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware, as you may need to reuse it.
- Install the New Module: Mount your new, pre-programmed ECM in place and securely fasten it.
- Reconnect Everything: Firmly plug the wiring harnesses into the new module until they click. Reconnect the negative battery terminal.
- Perform Security Relearn (If Needed): In many cases, a simple key cycle is enough. However, some GM vehicles require a security relearn procedure. This typically involves turning the key to ‘ON’ for 10-15 minutes, then ‘OFF’ for 10 seconds, repeating this three times. Your vehicle’s manual will have the specific procedure.
Verified Vehicle Compatibility
This Engine Control Module (interchangeable with part number 12629009) is a guaranteed fit for a wide range of General Motors vehicles. Please verify your specific model and options below:
Fitment Includes:
AVALANCHE 1500 (09-10), CORVETTE (09), ESCALADE / ESV / EXT (09-10), EXPRESS/SAVANA VANS (09), G6 (09), G8 (09), HUMMER H2 (09), IMPALA (09), MALIBU (09), SIERRA/SILVERADO 1500/2500/3500 (09-10), SUBURBAN (09-10), TAHOE (09-10), VUE (10), YUKON / XL (09-10), and more. Please check the detailed fitment list or contact us with your VIN to confirm compatibility.
Frequently Asked Questions
Do I need to do any programming myself?
No. This is the biggest benefit of our service. We program the engine computer with the latest GM software using the VIN you provide during checkout. It arrives ready for installation.
Is this a simple plug-and-play installation?
For most vehicles, yes. After physically installing the module, you may need to perform a simple security relearn procedure, which does not require any special tools. We include general instructions to guide you.
Will this fix my specific problem?
This module corrects issues directly caused by a faulty ECM, such as internal processor errors (P0601), communication faults (U0100), and driver circuit failures. While it solves many common problems, you should ensure your vehicle’s issue has been properly diagnosed.
Where do I provide my VIN?
After you complete your purchase, we will contact you for your vehicle’s 17-digit VIN. We cannot ship the part until we have this information to program it correctly.
What is the difference between part numbers 12625455 and 12629009?
These are interchangeable GM service numbers for the same hardware family. Our module is compatible with vehicles that originally came with either part number, as the critical factor is the correct software programming for your VIN.
Is this a new or used part?
This is a high-quality, tested, and verified used OEM part that has been inspected and programmed to function like new, ensuring OEM reliability without the high dealership cost.