Restore Peak Performance to Your GM Vehicle
Is your Cadillac XTS, Impala, or Traverse suffering from mysterious and frustrating issues? A flickering check engine light, unexplained stalling, poor fuel economy, or a complete no-start condition can often be traced back to a single, critical component: the Engine Control Module (ECM). As the central computer of your vehicle, the ECM is responsible for managing everything from fuel injection and ignition timing to transmission shifting and emissions control. When it begins to fail, the symptoms can be widespread and difficult to diagnose, leading to costly and unnecessary repairs.
This genuine GM Engine Control Module, part number 12666070, is the definitive solution to restore your vehicle’s factory performance, drivability, and reliability. We take the guesswork and complexity out of the replacement process. Unlike a generic module from a parts store or a salvage yard unit with an unknown history, this ECM comes professionally programmed with the latest GM-authorized software updates specifically for your vehicle. All we need is your Vehicle Identification Number (VIN) at the time of purchase to ensure a perfect match and seamless integration.
From the Diagnostic Bay
I once had a 2018 Impala come into the shop with a persistent P0300 random misfire code. The owner had already spent a small fortune replacing all the spark plugs, ignition coils, and even the fuel injectors at another shop, but the problem remained. The car would idle rough and hesitate on acceleration. After hooking up our diagnostic scanner, we noticed erratic data from the crankshaft position sensor, but the sensor itself tested fine. Experience told us to look upstream. We inspected the ECM wiring and found no issues. On a hunch, we connected a known-good ECM. Instantly, the engine smoothed out, and all sensor data stabilized. The original ECM had an internal fault that was corrupting the sensor signals, causing the misfire. This is a classic case where chasing symptoms instead of addressing the root cause—the failing computer—leads to wasted time and money. A pre-programmed ECM like this one would have solved his problem on the first try.
Is Your Vehicle Showing Signs of a Failing ECM?
A faulty ECM can manifest in numerous ways, often mimicking other component failures. If you’re experiencing any of the following issues, your engine computer could be the culprit. This 2017-2019 XTS ECM is the direct solution for these common problems:
- ✔ Check Engine Light: An illuminated or flashing Check Engine Light (CEL) with various trouble codes is the most common sign.
- ✔ Engine Stalling or Misfiring: The engine may stall unexpectedly, run rough, or misfire, especially under load.
- ✔ Poor Performance: Noticeable loss of power, hesitation during acceleration, and sluggish response.
- ✔ Reduced Fuel Economy: A sudden and unexplained drop in your vehicle’s gas mileage.
- ✔ Transmission Issues: Harsh shifting, delayed engagement, or getting stuck in one gear can be caused by poor communication from the ECM.
- ✔ No-Start Condition: The engine cranks but refuses to start, often due to the ECM not firing the fuel injectors or ignition coils.
- ✔ Intermittent Problems: Issues that come and go with changes in temperature or driving time, making diagnosis a nightmare.
The Power of VIN-Specific Programming
Modern vehicles are incredibly complex, and the ECM is tailored to the specific options and systems installed in your car from the factory. Simply installing a used or non-programmed module will not work; the vehicle’s anti-theft system will prevent it from starting, and it won’t have the correct software for your engine, transmission, and emissions equipment. Our process eliminates these headaches:
- You Purchase: Complete your order for this ECM.
- You Provide Your VIN: Reply to our confirmation email or message us with your 17-digit VIN.
- We Program: Our technicians use professional equipment to flash the module with the latest, most stable GM software release for your exact vehicle. This ensures optimal performance and compatibility.
- We Ship: We ship the ready-to-install module directly to you.
This service saves you a costly trip to the dealership, which often involves high labor rates and towing fees. For most applications, installation is straightforward, and the vehicle will start and run immediately. In some cases, a simple security relearn procedure (often called a “key cycle”) may be required, which can typically be performed without any special tools.
Complete Compatibility Information
This module is a direct replacement for several part numbers, ensuring a perfect fit and function. If your original module has one of the following numbers, this part is the correct replacement for you:
- 12666070 (Primary Part Number)
- 12667002
- 12667189
This 2017-2019 XTS ECM is also confirmed to fit the following vehicles and configurations:
- 2017 Cadillac XTS: Electronic Control Module; (3.6L), VIN 3 (8th digit, opt LFX)
- 2018 Cadillac XTS: Electronic Control Module; (3.6L), VIN 3 (8th digit, opt LFX)
- 2019 Cadillac XTS: Electronic Control Module; (3.6L), VIN 3 (8th digit, opt LFX)
- 2017 Chevrolet Caprice: Electronic Control Module; 3.6L
- 2017 Chevrolet Traverse: Electronic Control Module; (behind fan shroud)
- 2017-2019 Chevrolet Impala: Electronic Control Module
- 2017 Chevrolet Equinox: Electronic Control Module; (LH engine compartment)
- 2017 GMC Acadia: Electronic Control Module; VIN J (11th digit, Limited), (behind fan shroud)
- 2017 GMC Terrain: Electronic Control Module; (LH engine compartment)
- 2017 Buick Enclave: Electronic Control Module; (behind fan shroud)
- 2017 Buick Regal: Electronic Control Module; (LH engine compartment)
- 2017 Buick Verano: Electronic Control Module
Frequently Asked Questions
What exactly does an ECM do?
The Engine Control Module (ECM) is the main computer that controls your vehicle’s engine and powertrain. It takes data from dozens of sensors to manage fuel delivery, spark timing, emissions systems, and transmission operation to ensure the vehicle runs efficiently and smoothly.
How do I provide my VIN after purchase?
After you place your order, you can simply reply to your order confirmation email with your 17-digit VIN. You can also send it to us through the website’s messaging system. We cannot program and ship the module without it.
Is this a plug-and-play installation?
For the vast majority of vehicles, yes. Because we program it to your VIN, it’s ready for installation. In some cases, a simple security relearn procedure is needed, which involves turning the key on and off in a specific sequence. Instructions are readily available online for this procedure.
Will this fix my check engine light?
If the check engine light and associated codes are caused by a faulty ECM, then yes, this part will resolve the issue. However, it’s crucial to ensure that the codes are not being caused by a separate faulty sensor or wiring issue before ordering.
Where is the ECM located on my vehicle?
The location varies by model. As noted in the fitment list, it can be behind the fan shroud (Traverse, Acadia, Enclave) or in the left-hand (driver’s side) engine compartment (Regal, Equinox, Terrain). Always disconnect the battery before attempting to replace the module.
What if I install it and my car doesn’t start?
First, double-check all connections and ensure the battery is fully charged. Next, attempt the security relearn procedure. If the vehicle still does not start, contact us immediately. An incorrect VIN is the most common cause of post-installation issues, so please verify the number carefully before sending it.