Will Your Car Pass Inspection with the Check Engine Light On?

If your check engine light is on, it can cause serious concerns when you’re preparing for a vehicle inspection. The short answer is no — in most cases, your car will not pass inspection with the check engine light on, especially if the issue is related to emissions.

Why Does the Check Engine Light Turn On?

The check engine light is a warning from your car’s onboard diagnostic system (OBD). It illuminates when the system detects a problem with the engine, exhaust, or emissions system. While it can sometimes be triggered by minor issues, it can also indicate serious mechanical or electrical failures that require attention.

Common Causes for the Check Engine Light:

• Faulty oxygen sensors
• Worn-out catalytic converter
• Loose or damaged gas cap
• Engine misfire
• Exhaust system issues

How Does the Check Engine Light Affect Vehicle Inspections?

During a vehicle inspection, especially emissions inspections, the check engine light is taken very seriously. Here’s why:

1. OBD-II System Check

Modern vehicles (1996 and newer) are equipped with the OBD-II system, which monitors various engine and emissions components. During the inspection, a mechanic will connect your car to a diagnostic tool to check the status of the OBD-II system. If the check engine light is illuminated, it typically indicates that there is an issue with the vehicle’s emissions system or other critical components.

• If the check engine light is on, your car will usually fail the inspection, especially if the problem is related to emissions.

2. Readiness Monitors

When the check engine light is on, certain readiness monitors may also fail. Readiness monitors are used to track the performance of your car’s emissions system components. If the OBD-II system detects a malfunction in a component, such as the catalytic converter or oxygen sensor, it will trigger the check engine light, and the car will fail the inspection.

3. Emissions Standards Compliance

Most regions have strict emissions standards that vehicles must meet in order to pass the inspection. If the check engine light is on, it usually indicates that the vehicle is not meeting emissions standards, meaning it could be producing harmful pollutants that are not acceptable under the law.

Can You Still Pass the Inspection If the Check Engine Light is On?

While it’s unlikely, there are some situations where you might still pass the inspection even with the check engine light on:

1. Non-Emissions Related Issues

If the check engine light is on but not related to emissions, such as an issue with the engine’s air intake system or a minor sensor malfunction, it may not affect the inspection, depending on the regulations in your area. However, this is rare, and the light will still likely cause the inspection to fail.

2. Resetting the OBD System

Some vehicle owners attempt to reset the OBD system by disconnecting the battery or using a diagnostic tool to clear the error codes before the inspection. While this might turn off the check engine light temporarily, the underlying problem may still exist. The system may also trigger the light again shortly after, leading to an automatic fail.

3. Emission-Related Repairs

If the issue that caused the check engine light to come on has been fixed before the inspection, the light will turn off and the vehicle can pass inspection. However, the OBD-II system may need a few driving cycles (50-100 miles) to reset and clear the readiness monitors before you can pass the inspection.

What Should You Do If the Check Engine Light is On Before the Inspection?

If you have a check engine light on before your inspection, here’s what you should do:

1. Get the Vehicle Diagnosed

Take your car to a mechanic and have them use an OBD-II scanner to read the trouble codes. The mechanic will identify the exact cause of the check engine light. This is the first step in addressing the issue.

2. Fix the Problem

Once the issue is diagnosed, have the necessary repairs done. Common repairs may include replacing faulty sensors, fixing a worn-out catalytic converter, or resolving engine misfires.

3. Clear the Codes

After the repairs are completed, the mechanic can clear the trouble codes from the OBD-II system. Once the issue is fixed, the check engine light should turn off, and the readiness monitors will need a few driving cycles to reset.

4. Retake the Inspection

Once the system is ready and the check engine light is off, your car will be able to pass the inspection.

FAQs

1. Can I pass an inspection with the check engine light on?

In most cases, no. If the check engine light is on, your vehicle is likely to fail the inspection, especially if it’s related to the emissions system.

2. Can I clear the check engine light before the inspection?

You can clear the light, but it’s not recommended unless the underlying issue is repaired. Simply clearing the codes won’t fix the problem and may trigger the light to come back on soon after.

3. What is the best way to prepare for a vehicle inspection with the check engine light on?

The best approach is to get the vehicle diagnosed, repair the issue, and ensure that the OBD-II system is reset before the inspection.

4. How much does it cost to fix the issue that triggered the check engine light?

The cost of repairs depends on the issue. Minor issues, like a loose gas cap, can be inexpensive, but more serious problems like replacing a catalytic converter can cost several hundred to a few thousand dollars.

5. Will I always fail an inspection if the check engine light is on?

While it’s not always guaranteed, most vehicles will fail the inspection if the check engine light is on, especially if it’s emissions-related.

Conclusion

In most cases, your car will fail the inspection if the check engine light is on, especially if the problem is related to the emissions system. The best course of action is to have your vehicle diagnosed and repaired as soon as possible to ensure it’s ready for inspection. Regular maintenance and prompt attention to check engine light warnings can help keep your car in good condition and pass the inspection with ease.