Restore Peak Performance to Your GM Vehicle
Is your 2005-2006 Saturn Relay, Chevy Equinox, or Pontiac G6 suffering from erratic behavior, poor fuel economy, or a no-start condition? These are classic signs of a failing Powertrain Control Module (PCM), the central computer of your vehicle. This genuine used PCM, part number 12591279, is the definitive solution to get your vehicle running reliably again. It serves as the brain, controlling everything from the fuel injectors and ignition timing to the transmission shift points. A faulty module can leave you stranded and facing a cascade of confusing check engine light codes.
From the Diagnostic Bay
We had a 2005 Chevy Uplander towed in that had its owner completely stumped. The van would intermittently stall while driving, sometimes refusing to restart for hours. The check engine light was on with a handful of seemingly unrelated codes for sensors that had already been replaced. After verifying power and ground to the module and checking the network communication, we pinpointed the issue: an internally failing PCM. The module was sending corrupt data, causing the vehicle to shut down unexpectedly. We installed a VIN-programmed replacement like this one, performed the security relearn, and the van ran perfectly. It’s a textbook example of how a failing 2005-2006 Relay PCM can mimic a dozen other problems.
Common Symptoms of a Failing PCM
- ✔ Check Engine Light is on with various communication or sensor codes (e.g., U-codes, P0601-P0606).
- ✔ Engine stalling, misfiring, or running rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Complete no-start condition where the engine cranks but won’t fire.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Issues with other electronic modules due to network communication failures.
- ✔ Failure to pass an emissions test.
Why Choose Our Pre-Programmed 2005-2006 Relay PCM?
Replacing a PCM isn’t just about swapping parts. The new module must be programmed with your vehicle’s specific Vehicle Identification Number (VIN) and the latest GM software updates to function correctly. Our service eliminates the most difficult step. We handle the programming for you before the part ever leaves our facility. Simply provide us with your VIN during checkout, and the module will arrive ready for installation. This saves you from expensive towing fees and costly programming charges at a dealership.
This unit is a tested, reliable component sourced from a salvaged vehicle. It is a direct replacement for part numbers 12591279 and 12591856. It is compatible with a wide range of GM vehicles, including:
- 2005 Chevrolet Equinox
- 2005-2006 Saturn Relay (3.5L)
- 2005 Chevrolet Malibu (New Style, 3.5L)
- 2005 Pontiac Montana (SV6)
- 2005 Buick Terraza
- 2005 Pontiac G6 (Sedan)
- 2005 Chevrolet Uplander
Please note that while the module comes programmed to your VIN, you will likely need to perform a simple security relearn procedure after installation. This can typically be done without special tools and involves a sequence of key turns. This procedure pairs the new PCM to your vehicle’s anti-theft system, allowing the engine to start and run.
Frequently Asked Questions
How do I provide my VIN number?
After you complete your purchase, you will receive instructions on how to send us your vehicle’s 17-digit VIN. We cannot ship the part until we have this information to program the module correctly.
Is this a plug-and-play part?
Almost. We program the module to your VIN, which handles the most complex part. However, you will need to perform a security relearn procedure (also known as a key relearn) after installation. This procedure is required to sync the new PCM with your vehicle’s anti-theft system and can usually be done in your driveway.
Will this fix my specific problem?
This PCM will correct issues directly caused by a faulty module. While the symptoms listed are common indicators, we always recommend a proper diagnosis by a qualified technician to confirm the PCM is the root cause of your vehicle’s problems before ordering.
What if my original part number is 12591856?
This module, part number 12591279, is a fully compatible and interchangeable replacement for part number 12591856. It will function identically once programmed for your vehicle.
Does this part come with a warranty?
Yes, all our electronic components come with a standard warranty. Please refer to the warranty tab on the product page for specific details and duration of coverage for this used part.