Programmed 2012-2014 CTS ECM 12651994 | VIN Flashed | Replaces 12643248

Restore Peak Performance to Your GM Vehicle with a VIN-Programmed ECM

If you’re dealing with a frustrating check engine light, erratic engine behavior, or a no-start condition, a failing Engine Control Module (ECM) is often the culprit. As a technician with over two decades of experience under the hood, I’ve seen firsthand how a faulty ECM can turn a reliable vehicle into a source of constant headaches. This isn’t just a component; it’s the brain of your engine, and when it falters, everything from fuel economy to transmission shifting can suffer. This listing is for a dependable replacement ECM, part number 12651994, which also directly replaces part numbers 12643248, 12652814, and AA69.

The biggest hurdle with ECM replacement has always been the expensive and time-consuming programming required at a dealership. We eliminate that step entirely. Before we ship your part, we flash it with the latest official GM software updates using the VIN you provide. This ensures that the module is perfectly matched to your vehicle’s specific configuration, restoring its original performance and efficiency. This is the same process a dealer would perform, but delivered directly to your door, ready for installation.

Is Your GM Vehicle Showing These Red Flags?

A failing ECM can manifest in numerous ways. If you’re experiencing any of the following, it’s a strong indicator that your engine’s computer may need replacement. This is especially true if you’ve scanned for codes and found internal processor faults.

• ✔ Check Engine Light is on with codes like P0601, P0606, or other U-series communication codes.
• ✔ The engine cranks but refuses to start.
• ✔ Noticeable drop in fuel economy (MPG).
• ✔ Stalling, stuttering, or hesitation during acceleration.
• ✔ Harsh or erratic automatic transmission shifting.
• ✔ Communication issues with your OBD-II scan tool.
• ✔ Intermittent problems that seem to have no logical cause.

A Straightforward Guide to Swapping Your ECM

While professional installation is always an option, many experienced DIYers can handle this job. The key is patience and following the proper procedure. As this is a pre-programmed module, no special scan tools are needed for programming.

1. Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 15 minutes to allow all systems to discharge before starting work.
2. Locate the ECM: On most of the compatible vehicles, the ECM is found in the engine bay, often on the driver’s side near the air filter box, behind the fan shroud, or on the passenger’s side firewall. Refer to your vehicle’s service manual for the exact location.
3. Disconnect and Remove: Carefully unplug the wiring harness connectors. Most have a locking tab that needs to be released. Once disconnected, unbolt the module from its mounting bracket and remove it from the vehicle.
4. Install the New Module: Bolt the new, programmed ECM into place. Securely reconnect the wiring harnesses, ensuring they click and lock into position. A clean, tight connection is critical.
5. Reconnect the Battery: Re-attach the negative battery terminal.
6. Perform Security Relearn: Many GM vehicles require a simple key-cycle security relearn procedure to sync the new ECM with the anti-theft system. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this sequence three times. Your vehicle’s specific procedure is readily available online.

Verified Compatibility for Your GM Vehicle

We guarantee this module will function correctly for the following makes and models when you provide your VIN for programming. Please match your original part number or vehicle application from the list below.