Is Your GM Truck Experiencing Critical Performance Issues?
If your 2012-2016 Sierra, Silverado, or other compatible GM vehicle is suffering from erratic behavior 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 is responsible for managing everything from fuel mixture and ignition timing to transmission shifting and emissions control. When it malfunctions, it can cause a cascade of problems that are frustrating and difficult to diagnose.
This genuine GM Engine Control Module, part number 12670335, is the definitive solution to restore your vehicle’s factory performance and reliability. Unlike generic modules that require expensive dealership visits for programming, this unit arrives at your door fully programmed to your vehicle’s specific Vehicle Identification Number (VIN). We load the latest GM-certified software updates, ensuring optimal performance, fuel efficiency, and compatibility right out of the box.
From the Diagnostic Bay
We had a 2014 Silverado 2500 with the 6.0L V8 come in on a tow truck. The owner said it would run fine for about 15 minutes, then suddenly stall and refuse to restart for an hour. He had already replaced the fuel pump and crank sensor with no luck. We hooked up our scanner and saw intermittent communication loss with the ECM. After confirming all power and ground circuits to the module were solid, we knew the ECM’s internal processor was failing under heat. We installed one of these VIN-programmed modules, performed the quick security relearn, and the truck fired up instantly. The customer called a week later to say it had never run better. It’s a classic case of a faulty ECM mimicking other component failures.
Common Symptoms of a Failing GM ECM
- ✔ Persistent and illuminated Check Engine Light (CEL)
- ✔ Engine misfires, stumbling, or rough idling
- ✔ Unexplained drop in fuel economy
- ✔ Vehicle enters ‘limp mode’ with reduced power
- ✔ Harsh or erratic automatic transmission shifting
- ✔ Intermittent or complete failure to start
- ✔ Communication errors with diagnostic scan tools
Why Choose Our Pre-Programmed 2012-2016 Sierra 2500 ECM?
The key to a successful ECM replacement is the programming. This isn’t just a part; it’s a comprehensive service. Your vehicle’s VIN contains critical information about its specific engine, transmission, emissions equipment, and other factory options. Our process ensures this 2012-2016 Sierra 2500 ECM is a perfect digital match for your truck. This eliminates compatibility conflicts and ensures all systems function as the manufacturer intended. By handling the programming before shipment, we save you hundreds of dollars in dealership fees and days of vehicle downtime.
Installation is straightforward for a DIY mechanic or any professional technician. Once the old module is removed, this unit bolts directly in its place. After connecting the harnesses, a simple security relearn procedure may be required, which can often be done without special tools. This ensures your vehicle’s anti-theft system recognizes the new ECM, allowing the engine to start and run.
This module is a direct replacement for a wide range of part numbers, including 12668866, 12668994, 12643636, 12663405, and more, and fits an extensive list of GM vehicles. While we highlight its application for the 2012-2016 Sierra 2500 ECM, it is also the correct computer for many Cruze, Sonic, Express/Savana vans, and other models. Please verify your part number and check the fitment list to ensure compatibility.
Frequently Asked Questions
What is an ECM and why is it so important?
The Engine Control Module (ECM), sometimes called a Powertrain Control Module (PCM), is your vehicle’s main computer. It controls the engine’s fuel delivery, spark timing, and emissions systems to ensure optimal performance, economy, and low emissions. A faulty ECM can cause a wide variety of serious running issues.
Is this part ready to install when I receive it?
Yes, it is. We program the module with the latest GM software using the VIN you provide during checkout. This makes the physical installation plug-and-play. However, you may need to perform a simple security relearn procedure (also known as a CASE relearn) to sync the new ECM with your vehicle’s anti-theft system.
Where do I provide my vehicle’s VIN?
After you complete your purchase, you will need to send us your 17-digit VIN. You can typically add it as a note to the seller during checkout or send it to us in a message referencing your order number. We cannot ship the part until we have your VIN to program it.
Will this ECM fix my vehicle’s problem for sure?
This module will correct issues directly caused by a faulty ECM. While the symptoms listed are common for ECM failure, they can also be caused by other failing sensors or wiring issues. It is essential to have a proper diagnosis performed to confirm the ECM is the point of failure before ordering.
What is a security or CASE relearn?
A security relearn is a procedure that allows your vehicle’s Body Control Module (BCM) and anti-theft system to recognize the new ECM. It usually involves a sequence of turning the key on and off for set periods. A Crankshaft Variation (CASE) relearn helps the ECM fine-tune its readings from the crank sensor. A professional scan tool is often required for the CASE relearn.
Does this part fit vehicles other than the Sierra?
Absolutely. This ECM is used across a wide variety of GM vehicles, including the Silverado 2500/3500, Express/Savana vans, Chevrolet Cruze, Sonic, Trax, Buick Encore, and more. Please review the detailed fitment list on this page to confirm it is the correct part for your specific year, make, and model.