In previous articles, we introduced conceptual questions such as what I/M ReadNiess is and what role it plays in OBD2 scanners. So, how exactly is this function used? What role does it play in automotive diagnostics, and how is it related to vehicle emissions testing?
Today, we'll mainly use the Autel MK808Z automotive diagnostic tool as an example to explain how to check a car's I/M readiness status, enabling you to safely pass emissions tests, saving you time and effort, and preventing you from feeling distressed by failing emissions tests.
What is the I/M Readiness Status?
In a previous article, we explained in detail what the I/M readiness function is. To avoid confusion for readers who haven't read the previous article, I will provide a simple explanation here. Readers who wish to learn more can click the link below to read the full article.
I/M Readiness refers to the process of checking the engine and emission control systems using OBDII (On-Board Diagnostics II) during routine maintenance checks to ensure they are in normal working order.
I/M Readiness (Inspection and Maintenance Readiness) indicates whether your vehicle's self-diagnostic system has completed its evaluation of emission-related components. When your vehicle displays "Not Ready," it means that some systems have not yet completed their checks. Therefore, the vehicle may fail emission tests.
The I/M Readiness status involves multiple emission control components and can perform up to 11 system tests, including the following key areas:
- Evaporative Emission Control (EVAP)
- Oxygen Sensor
- Catalytic Converter
Autel OBD2 reader I/M Readiness status monitoring interface
What is Vehicle Emissions Testing?
If your car insurance or vehicle registration needs renewal, your vehicle may also require emissions testing or smog checks. In 1990, the U.S. Environmental Protection Agency (EPA) established a series of emissions standards to minimize harmful air pollutants emitted by motor vehicles. This means your car may need to be tested periodically to ensure it meets emissions standards and reduces its negative impact on the environment.
Preparations before scheduling testing:
1. Confirm your emissions test appointment time in advance and make an appointment.
2. Bring the required documents. While requirements vary by state, they typically include your vehicle registration, previous inspection report, and a letter from the department responsible for emissions testing.
3. Before heading out for your emissions test, it's best to use automotive diagnostic tools to perform an I/M Readiness check. While this check isn't mandatory, doing it before your scheduled test can save you time and effort from a failed test.
How to Check I/M Readiness with an Autel MK808Z?
Step 1: Connecting the Autel MK808Z to the car
The Autel MK808Z is a wired OBD2 scanner and does not come with a slave device. Therefore, the included mini USB cable is plugged into the OBD II port to connect the diagnostic tool and the vehicle, establishing a connection.
Step 2: Enter the diagnostic menu
After connecting the Autel MK808Z scanner, access the main page. Select the "Diagnostics" menu. The Autel MK808Z has automatic VIN recognition and scanning functions. Therefore, select EOBD > Autoscan. Before automatic scanning, ensure the ignition switch is on, but do not start the engine. Some vehicle models may not support automatic scanning; you can also manually select the vehicle brand and model.
Step 3: Enter the I/M readiness check state
Select I/M Readiness to enter. You will see two options: "Since DTCs cleared" and "This driving cycle". After clearing the fault codes, you need to check the I/M Readiness status to see if all emission detection systems are ready.
I/M Readiness Interface Status Classification and Meaning:
- OK: Indicates readiness
- N/A: This means it is not applicable to this vehicle.
- INC: This indicates that the task is not yet complete (not ready).
I/M Readiness Status Meaning On the Autel MK808Z
Step 4: Performing cyclic driving
This step is necessary when a system is not ready. When a system is not ready, it may be because some parts have not been restored to their original condition after repairs. In this case, a cycle of driving is required to bring the vehicle into full working order.
Cyclic driving procedure instructions:
1. Cold Start: After the vehicle has completely cooled down, start the vehicle and let it idle for approximately 3-5 minutes without pressing the accelerator.
2. Steady Speed Driving: Drive at a steady speed of 30–40 mph (approximately 48–64 km/h) for 5–10 minutes.
3. Acceleration and Coasting: Smoothly accelerate to approximately 55 mph (88 km/h), then release the accelerator to decelerate naturally; avoid sudden braking.
4. Parking and Idling: After parking, let the vehicle idle for a few minutes, observing for any abnormalities.
5. Repeat this cycle: To improve the success rate, it is recommended to perform at least 2-3 driving cycles.
Operation Reference Video:
Final Thoughts
The above describes the entire process of using the Autel MK808Z scanner to check I/M Readiness. You will pass the emissions test when all systems show as ready or only one system shows as not ready. These steps are not difficult, but they can save you time and effort, allowing you to pass the emissions test on the first try without affecting your subsequent tasks.
FAQs
Q1: Is only the Autel MK808Z capable of performing I/M readiness checks?
A: No. Almost all Autel scanners can perform this function. Whether it's a simple OBD II code reader or an advanced flatbed scanner, they can all perform I/M Readiness checks. For example, the Autel MS300 or Autel MS919.
Q2: What to do if you fail the emissions test?
A: Use automotive diagnostic tools to check for fault codes. Perform a cycle of driving the vehicle 2-3 times to check the I/M Readiness status until everything is ready. Then you can perform the emissions test again.
Q3: If only one item on the diagnostic scanner is not ready, can the test be passed?
A: While some states allow annual inspections to proceed with a “limited inadequacy” status, the safest approach is to ensure all systems are ready.
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