When you use a car scanner tool, you might encounter a “Not Ready” status, even after clearing trouble codes. This can be confusing and raise concerns, especially if you’re preparing for an emissions test. Understanding why your car scanner indicates “Not Ready” and how to address it is crucial for vehicle maintenance and compliance. This article will delve into the concept of OBD-II readiness monitors and explain how to ensure your vehicle is actually ready.
What Does “Not Ready” Really Mean on a Car Scanner?
Modern vehicles are equipped with sophisticated onboard diagnostic systems (OBD-II) that continuously monitor various engine and emission control components. These systems employ “readiness monitors,” which are essentially self-tests that the car’s computer performs to ensure all systems are functioning correctly. These monitors cover critical areas like the catalytic converter, oxygen sensors, evaporative emissions system, and EGR system.
When a car scanner reports “Not Ready,” it signifies that one or more of these readiness monitors have not yet completed their diagnostic tests since the last time the Diagnostic Trouble Codes (DTCs) were cleared or the battery was disconnected. It does not necessarily mean there’s a problem with your car right now, but rather that the system hasn’t confirmed everything is working correctly after a reset.
Why Your Car Might Show “Not Ready” After Using a Scanner
The most common reason for a “Not Ready” status after using a car scanner is clearing Diagnostic Trouble Codes (DTCs). When you clear codes with a scanner, you’re essentially resetting the OBD-II system. This reset also sets all readiness monitors to an “incomplete” or “Not Ready” state. The vehicle needs to re-run its self-tests to confirm everything is still functioning as expected after the codes were cleared.
Disconnecting your car battery can also cause readiness monitors to reset to “Not Ready.” Any event that disrupts the car’s computer memory can lead to the need for these monitors to run again.
The Solution: The Drive Cycle to Achieve Readiness
To get your car’s readiness monitors to switch to “Ready,” you typically need to perform what’s known as a “drive cycle.” A drive cycle is a specific set of driving conditions designed to allow the car’s computer to run all the necessary self-tests for the readiness monitors. Different manufacturers and even different models within the same brand may have slightly varied drive cycle procedures.
For Chrysler vehicles, specific drive cycles are outlined to address different monitors. Here are a few examples to illustrate the concept:
Chrysler General Drive Cycle Example:
This drive cycle is a more general approach to set various monitors.
- Warm-up: Start your vehicle and let it idle for five minutes to reach closed loop operation.
- Highway Driving: Drive at a steady speed between 40 and 60 mph for 8 minutes.
- Idle: Stop the vehicle and let it idle for 3 minutes.
- City Driving: Drive at a steady speed above 20 mph for 2 minutes.
- Cool Down: Turn the engine off and leave the key off for ten minutes.
Chrysler Catalyst Monitor Drive Cycle Example:
This drive cycle specifically targets the catalyst monitor.
- Idle Warm-up: Idle your vehicle for five minutes to reach closed loop operation.
- Moderate Speed Driving: Drive at a steady speed between 30 and 45 mph for 2 minutes.
Why Specific Drive Cycles Matter
Manufacturers like Chrysler design these specific drive cycles because each monitor has particular conditions it needs to experience to run its diagnostic test effectively. These conditions can include engine temperature, speed, load, and time. Following the correct drive cycle is essential to ensure all monitors are set to “Ready.”
Using Your Car Scanner to Confirm Readiness
After performing a drive cycle, you can use your car scanner tool again to check the status of the readiness monitors. A good car scanner will display the status of each monitor (e.g., Catalyst Monitor, O2 Sensor Monitor, EVAP Monitor). Ideally, you want to see “Ready” or “Complete” for all applicable monitors.
If some monitors are still “Not Ready” after a drive cycle, you may need to repeat the drive cycle or consult your vehicle’s repair manual for more specific instructions. In some cases, underlying mechanical issues might prevent a monitor from setting to “Ready,” requiring further diagnosis and repair.
Conclusion: “Not Ready” is Temporary, Readiness is Key
Seeing “Not Ready” on your car scanner after clearing codes is a normal occurrence. It doesn’t automatically indicate a problem, but it does mean your vehicle’s OBD-II system hasn’t yet confirmed all emission control systems are functioning correctly since the reset. Performing the appropriate drive cycle, like the Chrysler examples provided, allows your car to run these self-tests and achieve a “Ready” status. Using your car scanner to monitor readiness is a valuable step in ensuring your vehicle is not only running well but also compliant with emission standards. If “Not Ready” persists despite drive cycles, it’s wise to seek professional diagnosis to rule out any underlying issues.
