Is your 2003-2004 Buick Regal, Impala, or Grand Prix suffering from perplexing engine problems? Issues like stalling, rough idling, a persistent check engine light, or even a complete no-start condition often point to a failing Powertrain Control Module (PCM). This component is the central computer of your vehicle, managing everything from fuel injection and ignition timing to transmission shifting. When it fails, the entire vehicle’s performance and reliability are compromised. This replacement PCM, part number 12583826, is the definitive solution to restore your vehicle’s factory performance and get you back on the road with confidence.
This isn’t just a generic, off-the-shelf part. We provide a fully programmed module tailored specifically to your car. Upon purchase, you will provide us with your vehicle’s unique 17-digit Vehicle Identification Number (VIN). Our technicians will then flash the module with the latest, most stable General Motors software updates for your exact make and model. This critical step ensures seamless communication between the PCM and all other vehicle systems, eliminating the need for expensive dealership programming and complex setup procedures. It’s designed to be a direct-fit, effective replacement for the original unit.
From the Diagnostic Bay
I once had a 2003 Buick LeSabre come into the shop with a classic complaint: intermittent stalling at red lights and a check engine light with a code for the crankshaft position sensor. The owner had already replaced the sensor twice with no luck. After hooking up the scan tool and watching the live data, I noticed the sensor signal was dropping out randomly, but the wiring and sensor itself tested fine. The real culprit? The PCM’s internal processor was failing, unable to consistently interpret the sensor’s signal. We installed a VIN-programmed PCM like this one, performed the security relearn, and the car ran perfectly. It’s a textbook example of how a faulty module can send you chasing phantom sensor issues, wasting time and money.
Is Your Vehicle Exhibiting These Symptoms?
A failing PCM can manifest in numerous ways. If you’re experiencing any of the following, a faulty engine computer could be the root cause:
- ✔ Unexplained Check Engine Light (CEL) illumination, often with communication-related (U-codes) or processor fault codes.
- ✔ Engine stalling, stumbling, or hesitating during acceleration.
- ✔ Rough or erratic idling.
- ✔ A complete no-start condition where the engine cranks but won’t fire up.
- ✔ Poor fuel economy and reduced engine power.
- ✔ Harsh or incorrect automatic transmission shifting.
- ✔ Seemingly random electrical issues or warning lights on the dashboard.
The Importance of a VIN-Programmed 2003-2004 Regal PCM
The 3.8L V6 engine used in these GM vehicles is legendary for its durability, but the electronics that control it are complex. A generic or non-programmed module simply will not work. Your vehicle’s VIN contains specific information about its engine, transmission, emissions equipment, and factory options. Our programming process uses this data to load the correct software, ensuring every parameter is set to GM’s original specifications. This guarantees proper engine performance, fuel efficiency, and transmission function, and is essential for passing emissions tests in many states.
This module is a direct replacement for service numbers 12583826 and 89017735. Installation is straightforward for a knowledgeable DIYer or any professional technician. After installing the module, you may need to perform a simple security relearn procedure (often called Passlock or Passkey relearn) to sync the new PCM with your vehicle’s anti-theft system. This procedure can typically be done without special tools and instructions are widely available.
Guaranteed Fitment
This Powertrain Control Module is a confirmed fit for the following vehicles. Please verify your vehicle and options match the list below:
- Buick Regal: 2003-2004 (Electronic Control Module; LH engine compartment)
- Buick LeSabre: 2003 (Electronic Control Module; LH engine compartment, ID 12583826)
- Buick Park Avenue: 2003-2004 (Electronic Control Module; LH front engine compartment)
- Chevrolet Impala: 2003 (Electronic Control Module; LH engine compartment, 3.8L, ID 12583826 or 89017735)
- Chevrolet Monte Carlo: 2003 (Electronic Control Module; LH engine compartment, 3.8L, ID 12583826)
- Pontiac Bonneville: 2003 (Electronic Control Module; LH engine compartment, ID 12583826)
- Pontiac Grand Prix: 2003 (Electronic Control Module; LH front engine compartment, 3.8L, ID 12583826)
Frequently Asked Questions
What is a PCM and what does it do?
The Powertrain Control Module (PCM) is your car’s main computer. It controls all aspects of the engine and transmission to ensure optimal performance, fuel economy, and emissions. It’s the brain of your vehicle’s powertrain.
Is this part ready to install out of the box?
Yes, this PCM comes pre-programmed to your vehicle’s VIN. After physical installation, you may need to perform a security relearn procedure, which syncs the module to your car’s anti-theft system. This procedure typically does not require special tools.
Where do I find my VIN?
Your 17-digit Vehicle Identification Number (VIN) can be found on your vehicle’s registration, insurance card, or on a metal plate on the driver’s side of the dashboard, visible through the windshield.
What happens if I install this without providing a VIN?
The module will not function correctly. It must be programmed with your specific VIN to communicate with your vehicle’s other systems and operate the engine properly. We cannot ship the part until we receive your VIN.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM, then yes, this part will resolve the issue. However, it’s crucial to properly diagnose the problem first, as the light can be triggered by many other components like sensors or wiring issues.