Last updated on July 19th, 2026 at 12:27 pm
The PCM/ECM in the 2006 Pontiac Montana 3.9L controls engine and transmission functions. Failure can cause diagnostic trouble codes such as P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, and P1621, leading to check engine light illumination and drivability issues.
The engine control module (ECM) and powertrain control module (PCM) in your 2006 Pontiac Montana 3.9L are critical for managing engine and transmission operations. This guide covers common failure symptoms, the replacement procedure, and important factory cautions. You will learn about the module’s location, the book labor times, and the necessity of capturing data before removal. Also covered are relevant service bulletins and the diagnostic trouble codes that indicate internal module faults. Understanding these aspects helps you make informed decisions about repair or replacement.
The PCM/ECM in the 2006 Pontiac Montana 3.9L manages fuel injection, ignition timing, transmission shifting, and emissions controls. It receives sensor inputs and adjusts parameters for optimal performance and fuel economy. Failure can lead to drivability issues and diagnostic trouble codes. When you need a new module, you can find replacement engine computers for the Pontiac Montana from suppliers that offer pre-programmed units, ensuring a straightforward installation without the need for additional programming steps.
The factory removal procedure reaches the control module next to the air cleaner assembly. The book time for module R&R is 0.9 hours, and the relearn procedure adds 0.5 hours. Replacement involves disconnecting the battery, accessing the module, removing the electrical connectors, and installing the new unit. After installation, a relearn procedure using a scan tool is required to restore the captured data. The module is secured with fasteners; ensure proper torque when reinstalling.

Work with the ignition off, and treat the module as static-sensitive: avoid touching the connector pins at any point.
| Operation | Configuration | Book Time |
|---|---|---|
| Engine Control Module R&R | All configurations | 0.9 hr |
| Engine Control Module Relearn | All configurations | 0.5 hr |
| Powertrain Control Module Relearn | All configurations | 0.5 hr |
| Powertrain Control Module R&R | All configurations | 0.9 hr |
The factory procedure requires using a scan tool to capture ECM/PCM data before removal, then restoring that data into the new module after installation. This ensures the module retains vehicle-specific settings. Flagship One provides a VIN-programmed replacement unit that arrives with the correct programming already applied, eliminating the need for the data capture and restore steps. This simplifies the replacement process and reduces the chance of errors.
The 2006 Pontiac Montana may experience no-start, stalling, misfire codes, or transmission shifting issues when the PCM/ECM fails. The check engine light may illuminate with codes such as internal control module fault indicating a problem within the module. Other codes like P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, and P1621 may also appear. Communication with a scan tool may be lost, and the vehicle may enter a reduced-power mode.
The following diagnostic trouble codes are documented for the 2006 Pontiac Montana 3.9L PCM/ECM: P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, P1621. These codes indicate internal module faults that require diagnosis and repair.
Two factory service bulletins apply to the 2006 Pontiac Montana 3.9L. Bulletin #06-06-04-003D (March 20, 2007) addresses a Service Engine Soon light with DTCs P1404 and/or P0404, requiring installation of an EGR valve kit and PCM reprogramming. Bulletin #05-06-04-060 (September 23, 2005) covers multiple module DTCs P0601, P0602, P0603, P0604, and P1621 shared in multiple modules. These bulletins provide guidance for diagnosing and repairing these conditions.
| Bulletin | Subject | What It Addresses |
|---|---|---|
| 06-06-04-003 | Service Engine Soon (SES) Light Illuminated, Multiple Powertrain Control Module (PCM) Diagnosti | Some customers may comment on a Service Engine Soon (SES) light illuminated on the instrument cluster. Some vehicles may have previously been serviced for this… |
| 05-06-04-060 | Powertrain Control Module (PCM), Engine Control Module (ECM), Transmission Control Module (ECM) | — |
The book time for PCM R&R is 0.9 hours, plus 0.5 hours for the relearn procedure. The module is located next to the air cleaner assembly.
Yes, the factory procedure requires using a scan tool to capture ECM data before removal. This data must then be restored into the new module after installation.
Common internal fault codes include P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, and P1621. These codes point to module issues that may require replacement.
For your 2006 Pontiac Montana 3.9L, you can choose between repairing the existing PCM/ECM or replacing it with a refurbished unit. Refurbished modules from Flagship One arrive pre-programmed with your VIN, saving the time and complexity of the factory data capture and restore steps. This ensures a direct swap with minimal downtime.

Flagship One stocks a refurbished, VIN-programmed PCM for the 2006 Pontiac Montana with a lifetime warranty, free shipping and no core charge. The full Pontiac Montana module lineup covers other engine configurations as well.
The 2006 Pontiac Montana 3.9L PCM/ECM is a critical component for engine and transmission control. Understanding its symptoms, replacement procedure, and the importance of data capture helps you make informed decisions. Flagship One offers pre-programmed units that simplify the process, allowing you to get back on the road quickly.