Fleet Vehicle Aftermarket Calibrations may Limit Vehicle Speed, Reduce Engine Power, and Cause Vibration at Idle

Vehicle speed may be limited to 70 mph (112 km/h) on some 2015-2021 Colorado and Canyon models equipped with the 2.5L engine (RPO LCV)) that are fleet vehicles. Some vehicles also may have limited power or may have a vibration at idle without any DTCs set or the Check Engine MIL illuminated.

These fleet vehicles, which may be equipped with RPO VZ8, may have an aftermarket Engine Control Module (ECM) calibration installed that limits the vehicle speed, total power output and reduces vehicle idle speed. The reduced idle speed can create a vibration at idle.

If the vehicle is no longer owned by the original fleet customer, the aftermarket calibrations may still be installed in the ECM. Verify the current ECM calibrations are not the original factory calibrations following the calibration verification process using the Tech 2 or GDS 2 that are covered in Bulletin #09-06-04-026T. (Fig. 14)


Fig. 14


If the vehicle is no longer owned by the fleet customer and the current customer wants the vehicle returned to the factory specifications, the customer will need to purchase an ECM and have it programmed with the factory calibrations.

If the vehicle is still owned by the fleet company, notify the driver or fleet management company of the vehicle that the limited speed and reduced power conditions are due to the aftermarket calibration installed in the ECM.


– Thanks to David Rutkowski

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