Is Your GM Vehicle Running Rough, Stalling, or Showing a Check Engine Light?
The Engine Control Module (ECM), often called the engine computer, is the electronic brain of your vehicle. It controls everything from fuel injection and ignition timing to emissions systems and transmission shifting. When it starts to fail, it can cause a cascade of confusing and frustrating problems that can be difficult to diagnose. If you’re experiencing erratic engine behavior, poor fuel economy, or a persistent check engine light with communication-related trouble codes, your ECM may be the culprit. This genuine used GM ECM 12669908 is the reliable and cost-effective solution to restore your vehicle’s performance and get you back on the road with confidence.
From the Diagnostic Bay
We had a 2018 Chevy Equinox come into the shop with a complaint of harsh shifting and intermittent stalling at stoplights. The customer had already replaced the transmission fluid and a couple of sensors with no luck. The transmission codes were intermittent and didn’t point to a specific solenoid or internal failure. After hours of chasing wires, we checked the data stream from the ECM to the TCM (Transmission Control Module). We noticed periodic data dropouts. On a hunch, we connected a known-good ECM. Instantly, the communication stabilized, the shifting smoothed out, and the stalling disappeared. It wasn’t a transmission problem at all; the failing ECM was sending corrupt data, causing the transmission to behave erratically. This is a classic example of how a faulty engine computer can manifest as a completely different issue.
Symptoms of a Failing Engine Control Module
A failing ECM can produce a wide range of symptoms. If your vehicle is exhibiting any of the following, it’s time to consider a replacement:
- ✔ Check Engine Light: The most common indicator. Codes may relate to module communication errors (U-codes), sensor circuits, or general performance issues.
- ✔ Engine Stalling or Misfiring: The ECM may fail to correctly time spark or fuel delivery, leading to rough running, misfires, or unexpected stalling.
- ✔ No-Start Condition: A completely failed ECM can prevent the engine from starting at all by cutting off signals to the fuel pump or ignition system.
- ✔ Poor Performance & Fuel Economy: Incorrect calculations for the air-fuel mixture can lead to a noticeable drop in power, acceleration, and miles per gallon.
- ✔ Transmission Shifting Problems: The ECM works closely with the Transmission Control Module (TCM). A faulty ECM can cause late or harsh shifts, or the transmission may get stuck in one gear (limp mode).
- ✔ Intermittent Electrical Issues: Seemingly unrelated problems with cooling fans, A/C, or other systems can sometimes be traced back to a failing ECM.
The Solution: A VIN-Programmed GM ECM 12669908
Replacing a modern ECM isn’t as simple as swapping parts. Each module is programmed specifically for the vehicle it’s installed in, containing information about the VIN, engine type, transmission, and factory options. Our process eliminates the guesswork and the need for expensive dealership programming tools. We take a genuine, tested, used ECM and program it with the latest GM-certified software using your vehicle’s unique VIN. This ensures that when you receive the part, it is correctly calibrated for your exact configuration, saving you time and money.
Critical Installation Information
While we handle the primary programming, one final step is required upon installation: the Vehicle Theft Deterrent System (VTDS) Relearn. This is a security procedure that syncs the new ECM to your vehicle’s ignition key and Body Control Module (BCM). Without this step, the vehicle’s security system will prevent the engine from starting.
NOTICE: This relearn procedure must be performed by the end-user or their mechanic using a compatible professional scan tool or GM’s TIS2Web programming system. It is the buyer’s responsibility to ensure this, as well as any other necessary relearns (such as crankshaft position variation, fuel injector flow rates, etc.), are completed for proper vehicle function.
Guaranteed Fitment for Service No. 12669908
This module is a direct replacement for units with service number 12669908. Please verify this number on your original ECM before ordering. This part is compatible with a wide range of GM vehicles, including:
- ACADIA: 2017 (VIN Z), 2018 (2.5L)
- ATS: 2017 (2.0L)
- CRUZE: 2017-2018 (Gasoline)
- CTS: 2017 (2.0L)
- EQUINOX: 2018 (1.5L, 2.0L), 2019 (1.5L, ID 12669908)
- LACROSSE: 2018 (2.5L)
- MALIBU: 2017, 2018 (1.8L, 2.0L)
- REGAL: 2018 (2.0L)
- VOLT: 2017-2018 (Gasoline)
Frequently Asked Questions
What is an ECM and what does it do?
The Engine Control Module (ECM) is your car’s main computer. It controls the engine’s critical functions, including fuel mixture, ignition timing, and idle speed, to ensure optimal performance, fuel efficiency, and low emissions.
Will this ECM be plug-and-play?
This ECM is pre-programmed to your vehicle’s VIN, which handles the most complex part of the setup. However, it is not fully plug-and-play. You MUST perform a security relearn (Vehicle Theft Deterrent System) upon installation for the vehicle to start. Other minor relearns may also be necessary depending on your specific vehicle.
How do I provide my VIN?
After you complete your purchase, you will need to send us your 17-digit Vehicle Identification Number (VIN). We cannot program and ship your ECM without it. Please double-check the VIN for accuracy to ensure correct programming.
What tools are needed for the theft deterrent relearn?
The theft relearn procedure typically requires a professional-grade bidirectional scan tool or access to GM’s official TIS2Web software service. Many independent repair shops have this capability. Some GM vehicles have a manual 30-minute key-on/key-off procedure, but a scan tool is the most reliable method.
Is this a new part?
No, this is a genuine, used OEM part that has been sourced from a salvaged vehicle. Each unit is inspected and tested before being programmed with the latest software for your VIN, offering a reliable and affordable alternative to a new dealership part.