Encountering an “OBDII not ready” status during an emission test can be frustrating, especially when you’re driving a reliable truck like the Silverado 5.3L. One common culprit, and often overlooked, could be related to aftermarket devices designed to disable Active Fuel Management (AFM), also known as cylinder deactivation. This article dives into a real-world scenario and expert advice to help you understand why your Range cylinder deactivation device might be the reason for your OBDII emission test failure.
The Case of the “Not Ready” Emission System
A Silverado owner recently shared their experience with a 2015 Sierra 2wd 4.3L V6. Prior to a scheduled state emission test, they wisely removed their Range AFM disabler. However, upon testing, the truck failed the “readiness” system check. Specifically, the O2 sensor and catalytic converter were flagged as “not completed.”
Alt text: Locating the OBDII port underneath the dashboard of a vehicle, a crucial step for emissions testing and diagnostics.
The mechanic confirmed that no recent battery replacements or code clearing had occurred, eliminating those common causes for readiness issues. This prompted the owner to question whether the removal of the Range AFM disabler could be the cause.
Range Technology Confirms AFM Disabler Impact on Emission Readiness
Seeking answers, the Silverado owner contacted Range Technology, the manufacturer of the AFM disabler. The response was direct and informative:
“As of right now, the AFM disablers are not emissions approved and can cause the vehicle to fail.”
“Disabling and then re-enabling the AFM system does reset the vehicle’s emissions readiness systems. We do recommend driving the vehicle for 50-100 total miles with the device removed to allow the emissions systems to fully reset before going to get the vehicle tested.“
Alt text: A Range AFM disabler device, commonly used to prevent cylinder deactivation in vehicles, which can impact emission system readiness.
This confirmation highlights a crucial point: removing a Range AFM disabler resets your vehicle’s emission readiness monitors. These monitors, including those for the O2 sensor and catalytic converter, need to run specific tests and driving cycles to achieve a “ready” status.
Understanding OBDII Readiness and Cylinder Deactivation Devices
Modern vehicles use sophisticated OBDII (On-Board Diagnostics II) systems to monitor various aspects of engine performance and emissions. Emission readiness monitors are a key part of this system, ensuring all emission-related components are functioning correctly.
AFM disablers work by preventing the vehicle from switching into cylinder deactivation mode. While this can be desirable for some drivers seeking consistent engine performance or sound, it interferes with the standard operation of the emission control systems, at least from the perspective of the OBDII monitors’ readiness checks.
When an AFM disabler is removed, the vehicle’s computer needs time to re-evaluate the emission systems and complete its self-tests. This process requires driving the vehicle through specific cycles that allow the monitors to run and confirm proper operation.
How to Ensure Emission Readiness After Removing a Range Disabler
If you use a Range AFM disabler on your Silverado 5.3L or similar vehicle and need to undergo an emission test, follow these steps:
- Remove the Range disabler: Do this well in advance of your emission test.
- Drive for 50-100 miles: This allows the vehicle’s emission monitors to reset and complete their tests. Vary your driving conditions, including highway and city driving, to facilitate a full driving cycle.
- Re-test: After driving the recommended mileage, take your Silverado for the emission test. The readiness monitors should now be in a “ready” state, allowing you to pass the test.
Alt text: A diagram of a Silverado 5.3L engine, highlighting components related to cylinder deactivation and the emission control system.
Important Note: Always consult your vehicle’s owner’s manual and the Range Technology documentation for the most accurate and up-to-date information regarding their devices and emission testing.
By understanding the impact of AFM disablers on emission readiness, you can avoid unexpected failures and ensure your Silverado 5.3L is ready for its next emission test. Driving your vehicle adequately after removing the device is crucial for a successful outcome.
