Restore Your Vehicle’s Core Performance and Reliability
Is your Cadillac XTS, Impala, or other GM vehicle suffering from frustrating issues like intermittent stalling, a persistent Check Engine Light, or a sudden drop in fuel economy? These are classic signs of a failing Engine Control Module (ECM). As the central computer for your engine, a faulty ECM can disrupt everything from fuel injection and ignition timing to transmission shifting. Don’t let a failing module leave you stranded or dealing with unpredictable performance. This replacement ECM, part number 12667002, is the definitive solution to restore your vehicle’s factory operation.
With over 20 years of hands-on diagnostic experience, I’ve seen firsthand how a failing ECM can cause a cascade of confusing problems. This isn’t just a replacement part; it’s a direct-fit, reliable fix that arrives ready for installation. We take the guesswork and extra cost out of the repair by programming the module to your specific vehicle using your VIN. This ensures all software is up-to-date with the latest GM calibrations, providing seamless integration and optimal performance right out of the box.
From the Diagnostic Bay
I remember a 2018 Impala that came into the shop with a ghost-in-the-machine problem. The owner complained of random stalling at stoplights and a check engine light that would come and go. We checked everything—fuel pressure, sensors, wiring—and couldn’t find a consistent fault. Finally, a deep scan revealed intermittent communication loss with the ECM (a U0100 code). The internal processor was failing under heat soak. Instead of a costly dealership visit for a new module and programming, we installed a VIN-matched unit just like this one. The car was back on the road the same day, running perfectly, and the customer saved hundreds.
Common Signs of a Failing Engine Computer
- âś” Check Engine Light is illuminated, often with codes like P0601, P0606, or other communication faults.
- âś” The engine cranks but refuses to start.
- âś” Intermittent stalling or rough idling, especially when the engine is warm.
- âś” Noticeable decrease in fuel efficiency.
- âś” Poor acceleration or hesitation during gear shifts.
- âś” Failure to pass state emissions testing.
- âś” Other warning lights (like traction control) may appear due to lost communication with the ECM.
A Straightforward Guide to Installation
Installing your replacement 2017-2019 XTS ECM is a manageable job for a DIY enthusiast. Since the module comes pre-programmed, no special scan tools are needed for the initial setup. Just follow these general steps:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait a few minutes to ensure the system is fully discharged.
- Locate the ECM: The location varies by model. It’s often found in the engine compartment (sometimes on the LH side or behind the fan shroud) or under the dashboard. A quick search for your specific model will confirm its location.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once disconnected, unbolt the old ECM from its mounting bracket.
- Install the New Module: Mount the new ECM securely onto the bracket and reconnect all electrical connectors. Ensure they click firmly into place.
- Reconnect Power: Reattach the negative battery terminal.
- Final Steps: Some vehicles may require a security relearn procedure, which typically involves cycling the key in the ignition. This simple process allows the new ECM to sync with your vehicle’s anti-theft system. Consult your owner’s manual or a reliable online resource for the specific procedure for your car.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 12667002, 12666070, and 12667189. It is guaranteed to fit the following vehicles:
- 2017-2019 Cadillac XTS (3.6L, VIN 3, LFX)
- 2017-2019 Chevrolet Impala
- 2017 Chevrolet Caprice (3.6L)
- 2017 Chevrolet Traverse (Behind fan shroud)
- 2017 Chevrolet Equinox (LH engine compartment)
- 2017 GMC Terrain (LH engine compartment)
- 2017 GMC Acadia (VIN J, Limited, behind fan shroud)
- 2017 Buick Enclave (Behind fan shroud)
- 2017 Buick Regal (LH engine compartment)
- 2017 Buick Verano