Is Your Chevrolet Impala Running Rough? It Could Be The ECM.
If your 2017, 2018, or 2019 Chevrolet Impala is experiencing baffling issues like stalling, poor fuel economy, a persistent check engine light, or even a no-start condition, the root cause is often a failing Engine Control Module (ECM). The ECM is the brain of your vehicle’s engine, responsible for managing everything from fuel injection and ignition timing to emissions control and transmission shifting. When it fails, the symptoms can be widespread and frustrating, often mimicking other component failures and leading to costly, incorrect diagnoses.
This is a direct-fit replacement ECM, part number 12667002, designed to restore your vehicle’s original performance and reliability. We take the guesswork and hassle out of the replacement process. Unlike a generic module from a parts store or a salvage yard, this unit comes professionally programmed to your vehicle’s specific Vehicle Identification Number (VIN). This critical step ensures that the computer has the correct software and calibrations for your Impala’s specific engine, transmission, and options, making for a seamless installation and proper function right out of the box.
From the Diagnostic Bay
We had a 2018 Impala come into the shop with a complaint that was driving the owner crazy. The car would run perfectly for days, then suddenly stall at a stoplight and refuse to restart for 10-15 minutes. There were no consistent trouble codes, just a few random communication errors stored in history. We checked the fuel pump, ignition system, and sensors – all tested fine. After hours of diagnostics, we monitored the ECM’s internal temperature data stream. We noticed that right before a stall event, the processor temperature would spike erratically. We applied some freeze spray to the ECM case, and the car would start right up. It was a classic case of an internal ECM failure caused by thermal stress. Replacing the module with a properly programmed unit like this one solved the problem permanently, saving the customer from replacing more perfectly good parts.
Common Symptoms of a Failing 2017-2020 Impala ECM
- ✔ Check Engine Light: The most common indicator, often with codes related to processor faults (e.g., P0606), sensor circuits, or communication errors.
- ✔ Engine Stalling: The engine may stall unexpectedly while driving or at idle and may be difficult to restart.
- ✔ No-Start Condition: The engine cranks but refuses to start due to a lack of fuel or spark commands from the ECM.
- ✔ Poor Performance & Fuel Economy: You might notice a significant drop in power, rough idling, hesitation during acceleration, and a noticeable decrease in MPG.
- ✔ Transmission Shifting Issues: The ECM works with the Transmission Control Module (TCM), and a failing ECM can cause harsh shifting, delayed engagement, or the transmission getting stuck in one gear.
- ✔ Intermittent Problems: Issues may appear randomly, often getting worse as the engine warms up, making diagnosis extremely difficult.
The Importance of VIN Programming
Modern vehicles are complex, and the ECM is tailored to the exact specifications of the car it was built for. Simply installing a used or non-programmed module will not work. Your vehicle’s anti-theft system (Pass-Key/VATS) is integrated into the ECM, and without the correct VIN programming, the system will prevent the engine from starting. Our process eliminates this problem. By providing us with your VIN during checkout, you receive a module that is loaded with the latest GM-certified software for your specific vehicle. This ensures compatibility and allows for a much simpler installation process, often only requiring a simple security relearn procedure that can be done without a scan tool.
Installation Process
Replacing the ECM is a manageable task for a confident DIYer or any professional technician. While specific steps may vary slightly, the general process is as follows:
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate the ECM: On the 2017-2019 Impala, the ECM is typically located in the engine compartment. Consult a service manual for the exact location.
- Disconnect Connectors: Carefully release the locking tabs and disconnect the wiring harness connectors from the old ECM.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Mount the new, pre-programmed ECM and securely reconnect the wiring harnesses.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn (if necessary): In many cases, you will need to perform a security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating this cycle three times. This allows the new ECM to sync with your vehicle’s anti-theft system.
This module is also a direct replacement for part numbers 12666070 and 12667189 and fits a wide range of other GM vehicles. Please verify the fitment list to ensure compatibility with your specific make, model, and year.
Frequently Asked Questions
Do I need to do anything after installing this ECM?
Because this module comes programmed to your VIN, the main step after installation is the security relearn procedure, also known as the VATS relearn. This process syncs the new computer to your car’s existing keys and anti-theft system. It can typically be done without special tools and instructions are readily available online.
What information do you need from me?
We require your vehicle’s 17-digit Vehicle Identification Number (VIN) to program the module correctly. Please provide your VIN at the time of purchase to avoid any shipping delays.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the old ECM, then this replacement part will solve the problem. However, if the light is on due to a faulty sensor or another component, that separate issue will still need to be addressed. This module will restore the computer’s ability to correctly diagnose the system.
Is this a new or used part?
This is a high-quality, tested, and verified OEM part that has been programmed with the latest vehicle-specific software from GM. It is guaranteed to function to original factory specifications.
Where is the ECM located on my 2017 Impala?
On the 2017-2019 Chevrolet Impala, the Electronic Control Module (ECM) is typically located in the engine bay, often on the driver’s side near the fuse box or air filter housing. Always consult a repair manual for your specific vehicle to confirm the location before beginning work.