Is Your Cadillac STS Running Rough, Stalling, or Showing a Check Engine Light?
If you’re dealing with frustrating engine problems like erratic idling, poor fuel economy, a no-start condition, or persistent diagnostic trouble codes that won’t go away, a failing Engine Control Module (ECM) is often the culprit. As a technician with over two decades of experience, I’ve seen how a faulty ECM can turn a reliable vehicle into a constant headache. The ECM is the brain of your engine, and when it starts to fail, the symptoms can be unpredictable and difficult to diagnose.
“A customer’s 2009 STS came in last week with intermittent stalling and a P0606 code (ECM Processor Fault). We spent an hour checking the wiring harness and verifying solid power and ground connections at the ECM connector—everything was perfect. This confirmed our initial suspicion: the internal processor was failing. We installed a VIN-programmed module just like this one, and the car started and ran perfectly, with the code gone for good. It’s a textbook fix for this issue.”
The Direct Solution: A VIN-Programmed 2009–2010 STS Engine Control Module
Don’t let a faulty computer keep you off the road. This Engine Control Module is the definitive solution for your 2009–2010 Cadillac STS. We take the guesswork and hassle out of the repair by pre-programming the module to your vehicle’s specific Vehicle Identification Number (VIN) before it ships. This means it arrives with the latest GM software updates already installed, ready for a straightforward installation. You get a reliable repair without the time and expense of a dealership visit for programming.
Common Symptoms of a Failing ECM:
- ✔ Check Engine Light is on with various communication or processor codes (e.g., P0601, P0606).
- ✔ Engine cranks but refuses to start.
- ✔ Unexplained stalling or hesitation while driving.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Rough or inconsistent engine idle.
- ✔ Automatic transmission shifting issues.
Plug-and-Play Installation: No Dealer Visit Required
Installing your replacement 2009–2010 STS ECM is a job most DIY mechanics can handle. By having us program it beforehand, you skip the most complicated step. Follow these general steps for a successful installation:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for the system capacitors to discharge.
- Locate the ECM: On the 2009-2010 Cadillac STS, the ECM is typically located on the left-hand (driver’s side) frame rail. Consult a service manual for the exact position.
- Disconnect Connectors: Carefully release the locking tabs and disconnect all electrical wiring harness connectors from the old module. Inspect the connectors for any signs of corrosion or damage and clean them if necessary.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket.
- Install the New Module: Mount your new, pre-programmed ECM in place and securely tighten the bolts.
- Reconnect Everything: Firmly plug the wiring harness connectors into the new module until they click into place. Reconnect the negative battery terminal.
- Final Steps: Some vehicles may require a security or crankshaft position sensor relearn procedure, which can often be done with a capable bi-directional scan tool or by following a specific key-on/key-off sequence.
Guaranteed Compatibility and Interchangeability
This module is a direct replacement for several part numbers, ensuring a perfect fit and function. If your original module has one of the following service numbers, this part is compatible:
Interchangeable Part Numbers: 12636659, 12639300, 1263605, 12628993, 12628911, 12625453, 12622175, 12630464, 12678512
This ECM Fits a Wide Range of GM Vehicles:
While this listing is focused on the Cadillac STS, this versatile module is also the correct fit for many other vehicles. Please verify your specific model and engine option below:
- Cadillac CTS (2009): 6.2L
- Cadillac DTS (2009-2011)
- Cadillac SRX (2009): 4.6L
- Cadillac STS (2009): 4.4L, 4.6L
- Cadillac STS (2010): 4.6L
- Cadillac XLR (2009)
- Chevrolet Colorado (2009-2012): 2.9L, 3.7L
- Chevrolet Corvette (2009): ZR1
- Chevrolet Trailblazer (2009): 6.0L
- GMC Canyon (2009-2012): 2.9L, 3.7L
- GMC Envoy (2009): 5.3L
- Hummer H3 (2009-2010): 3.7L
- Buick Lucerne (2009-2011): 4.6L
- Saab 9-7X (2009)
Provide your VIN at checkout, and we’ll handle the rest. Restore your vehicle’s performance and reliability today.