I/M Readiness (Inspection/Maintenance Readiness) indicates if your vehicle’s emissions control system has completed self-tests. It’s a basic feature accessible on most OBD2 scan tools, showing if your car is ready for state emissions inspection or if repairs have resolved issues.
Basically I use this to see if I will be able to pass state emission inspection. If I don’t see all monitors green (completed), I am not confident in passing it.
Yesterday I talked about reading fault codes, read here if you’ve missed it.
You can use readiness monitors for checking overall engine health, when checking a used vehicle, but mostly to make sure your car will pass the state emission inspection.
What Are I/M Readiness Monitors?
I/M Readiness Monitors are tests that your car’s computer runs to check if all the emissions control systems are working correctly. These monitors help determine if your vehicle is ready for an emissions inspection.
Types of Monitors
There are two main types of monitors:
- Continuous Monitors: These tests run all the time while you’re driving. They constantly check things like the ignition system and fuel system to make sure everything is working properly.
- Non-Continuous Monitors: These tests only run once per drive cycle when specific conditions are met. Examples include checking the catalytic converter or the EGR (Exhaust Gas Recirculation) system.
Completion Status
Each monitor can show one of two statuses:
- Complete/OK: The test has finished successfully, and everything is working as it should.
- Incomplete/Not OK: The test hasn’t finished or there’s a problem that needs attention.
Performing a Drive Cycle
To make sure all monitors run and complete their tests, you need to perform a specific series of driving steps called a drive cycle. Here’s how you can do it:
- Start and Idle: Make sure the engine is cold. Start your car and let it idle until the coolant temperature reaches about 160°F (71°C).
- Initial Acceleration: Accelerate smoothly to a speed between 40-55 MPH (65-88 KmH) and maintain this speed with about 25% throttle for 5 minutes.
- Deceleration: Gradually slow down to 20 MPH (32 KmH) or less without using the brakes, then come to a complete stop.
- Idle and Restart: Let the engine idle for 10 seconds, turn it off, wait for 1 minute, then restart the engine. Accelerate again to 40-55 MPH (65-88 KmH).
- Steady Speed: Keep driving at a steady speed for another 2 minutes at around 25% throttle.
- Final Deceleration: Slow down to 20 MPH (32 KmH) or less using the brakes or by downshifting. Let the engine idle for 10 seconds, turn it off, and wait for 1 minute.
Checking Readiness Monitors
After performing the drive cycle, you can check the status of your readiness monitors using an OBD2 scan tool. Simply connect the scanner to your car’s diagnostic port, and it will display whether each monitor is complete or still incomplete.
Frequently Asked Questions
- What does I/M Readiness mean? It shows whether your vehicle’s emissions systems have completed their self-tests.
- What does OBD Readiness mean? It indicates if your car’s OBD (On-Board Diagnostics) system has finished the necessary tests to monitor emissions.
- How do I check my monitor readiness? Use an OBD2 scanner to connect to your car and view the status of each emissions monitor.
- How do you use readiness monitors? They help ensure your vehicle meets emissions regulations and can identify if there are any issues that need fixing before an emissions inspection.
Example of bad monitors
Example of good monitors
Readiness monitors are part of Global OBD, so it is available on almost any scanner and every car with an OBD2 system. An easy way to check the overall engine state.
Important: Remember that readiness monitors will show no complete status after resetting codes. If you clear the check engine light, you will automatically get a no-complete status on most monitors until the ECU runs tests again.
P.S. The Extended version of this email course, including 60 video lessons to help you master DIY diagnostics, is available HERE.
Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)
