Description
2004 GMC Sierra 6.6L ECM / ECU – VIN Programmed | Updated
This Engine Control Module (ECM / ECU) is a genuine OEM replacement for all 2004 GMC Sierra 6.6L models.
Each unit is VIN-programmed, updated, and fully tested for a true plug-and-play installation with our cloning service.
Built to OEM standards for reliability, calibration accuracy, and long-term performance.
Strict Testing & Quality Assurance
Every ECU is inspected, refreshed, and verified through advanced diagnostic tools. Testing includes:
Complete communication & CAN-bus verification
Sensor input/output and signal integrity checks
Injector & ignition pulse simulation
Power, ground, and load-circuit analysis
Flash memory integrity and checksum validation
Thermal and voltage-stress testing to confirm reliability
Important Note
Some vehicles with IMMO or PATS require key programming after installation. This is normal.
For a 100% plug-and-play solution, we recommend using our full cloning service. We transfer all security data to the replacement unit.
A prepaid shipping label will be emailed to you. Allow you to mail in your original computer to us for full cloning.
If cloning is not selected, the ECU will be VIN programmed, and a key relearn will be required after installation.
Contact Us
Email: info@fixecm.com
Phone: Local: 647-247-8555 | Toll-Free: 1-800-915-5566
Mason Russell –
I needed a replacement ECM for my 2004 GMC Sierra 6.6L and was really impressed with how easy the whole process went. The unit arrived quickly, and I appreciated that the VIN programming was already done before shipping—made installation plug-and-play. The communication from the seller was top notch; they kept me informed every step of the way and answered my questions promptly. It feels like a solid, reliable part and has my truck running better than before. Definitely recommend this seller if you want a hassle-free experience.
Samuel Jenkins –
The ECU arrived quickly with free shipping and was already programmed for my 2004 GMC Sierra—plug-and-play made installation a breeze. Communication was spot on, and they answered all my questions right away.
Owen Reynolds –
I was a bit nervous about ordering an ECM online for my 2004 GMC Sierra, but this purchase exceeded my expectations. The module arrived quickly, and I appreciated the free shipping which saved me some extra cost. What really stood out was the plug-and-play setup—they had the ECM programmed specifically for my VIN before it shipped, so installation was straightforward with no hiccups. The quality of the part is top-notch, and my truck runs smoother than ever. I would definitely buy from them again if the need arises.
Chris Bailey –
I purchased the 12210729 ECM for my 2004 GMC Sierra, and the whole process was straightforward thanks to their professional VIN programming service. The unit arrived quickly with free shipping, which was a nice bonus. Everything worked perfectly right out of the box, and the communication from the team was excellent—they kept me informed every step of the way. Definitely a reliable source for quality parts and service.