If you’re dealing with a frustrating check engine light, unpredictable stalling, or a noticeable drop in performance on your Cadillac XTS, the root cause is often the Engine Control Module (ECM). As a 20-year veteran in automotive diagnostics, I’ve seen firsthand how a failing ECM can create a cascade of baffling problems. This isn’t just a part; it’s the brain of your engine, and when it falters, your vehicle’s reliability and drivability suffer. That’s why we offer a dependable solution: a genuine GM ECM, part number 12667189, programmed specifically for your vehicle.
Forget the hassle and high cost of dealership programming. When you order from us, you provide your Vehicle Identification Number (VIN), and we handle the rest. Our technicians will flash this 2017-2019 XTS ECM with the very latest GM-certified software releases. This ensures that all factory improvements for fuel efficiency, emissions, and performance are loaded and ready to go. Your new module arrives at your door prepared for installation, saving you time, money, and a trip to the service center.
Case Study: A Tricky Diagnosis
I remember a 2018 Impala that came into the shop with a complaint of intermittent stalling at stoplights. The owner had already been to two other places and replaced the spark plugs and a sensor with no luck. The car wasn’t storing any hard fault codes, making it a real diagnostic challenge. After monitoring live data, I noticed the fuel trim values were erratically spiking just before it would stall. Based on experience with hundreds of these 3.6L engines, I suspected the ECM’s internal processor was failing under certain conditions. We installed a VIN-programmed ECM, and the problem was solved instantly. It’s a perfect example of how the right part, correctly programmed, can be the definitive fix.
Common Signs of a Failing Engine Module
- ✔ Persistent Check Engine Light (CEL) with codes like P0601, P0606, or other internal processor faults.
- ✔ Engine stalling or misfiring for no apparent reason.
- ✔ A sudden decrease in fuel economy.
- ✔ The vehicle won’t start, but the battery and starter are good (no-crank/no-start).
- ✔ Poor or rough engine performance and hesitation during acceleration.
- ✔ Failure to pass state emissions testing.
A Straightforward Guide to Installation
Replacing your 2017-2019 XTS ECM is a manageable job for a confident DIYer or any professional mechanic. Follow these steps for a smooth installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the ECM: On these GM models, the ECM is typically found in the engine compartment, either on the driver’s side (LH) or mounted behind the fan shroud. Consult a service manual for your specific model if you’re unsure.
- Disconnect and Remove: Carefully unplug the electrical connectors. There are usually locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket and remove it.
- Install the New ECM: Mount the new module securely in place. Reconnect the electrical harnesses, ensuring they click firmly into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: Most GM vehicles require a simple key-cycle security relearn procedure to sync the new ECM with the vehicle’s anti-theft system. This can typically be done without special tools and instructions are widely available online or in your owner’s manual.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 12667002, 12666070, and 12667189. It is guaranteed to fit the following makes and models with the specified options:
- Cadillac XTS: 2017-2019 (3.6L, VIN 3 – 8th digit, opt LFX)
- Chevrolet Caprice: 2017 (3.6L)
- Chevrolet Traverse: 2017 (Behind fan shroud)
- Chevrolet Impala: 2017-2019
- Chevrolet Equinox: 2017 (LH engine compartment)
- GMC Acadia: 2017 (VIN J – 11th digit, Limited) (Behind fan shroud)
- GMC Terrain: 2017 (LH engine compartment)
- Buick Enclave: 2017 (Behind fan shroud)
- Buick Regal: 2017 (LH engine compartment)
- Buick Verano: 2017
Why do I need to provide my VIN?
Why do I need to provide my VIN?
Your VIN is essential for us to program the ECM with the correct software and calibrations for your vehicle’s specific features, engine, and transmission. This step ensures the module works perfectly right out of the box, just like one from the dealership.
Is this part difficult to install?
The physical installation is straightforward for most DIYers. Because it comes pre-programmed, you eliminate the most complex step. You may need to perform a simple security relearn procedure, which involves a series of key turns and can be done in your driveway.
What’s the difference between an ECM and a PCM?
The terms are often used interchangeably. An ECM (Engine Control Module) specifically manages engine functions. A PCM (Powertrain Control Module) is a more integrated unit that typically controls both the engine and the transmission. For the vehicles listed, this module serves as the primary engine controller.
Will this fix my car’s specific problem?
If your vehicle’s issues, such as a check engine light for an internal module fault (like P0601), are directly caused by a failing ECM, then yes, this part is the correct solution. It’s crucial to have a proper diagnosis to confirm the ECM is the point of failure before ordering.