Tips and Advice

Check Engine Light “Enlightenment”!

When your car’s Check Engine Light goes on, that usually indicates that there is some type of malfunction(s) in the engine emission control and operating systems or, occasionally, a transmission malfunction. It is also common to have more than one code appear simultaneously. These codes are conveniently stored in your car’s computer so that the issue can be assessed.

If your Check Engine Light is flashing or blinking, get it checked out ASAP! Operating a car with a flashing Check Engine Light could be potentially harmful to the vehicle, and subsequently cause damage that is expensive to repair. Staying on top of such issues will cause you fewer headaches later on, and get your car back on the road much faster!

If your car is showing a solid Check Engine Light, you should have it checked out relatively quickly—most definitely within a week or two. Some malfunctions can cause long-term problems if not addressed in a reasonable period of time, and it is better to know sooner rather than later what you’re dealing with!

After the code is initially checked, it is usually cleared to see if it returns. If the Check Engine Light reappears, you should bring in the vehicle for a full diagnostic evaluation. Oftentimes, the cause for the Check Engine Light is minor—such as a faulty or loose fuel cap—and thus an easy and inexpensive fix.

There are several hundred “codes” which could set off your car’s Check Engine Light. A code indicates which system to evaluate, not which part needs to be replaced. FYI: It is not uncommon for the Check Engine Light to come back on soon after a repair is made, as repairs to one system can trigger another code from the same or a different system.


Once the Check Engine Light code is erased, the car goes through a process of “resetting the monitors”, which essentially means rechecking the various systems.

A car cannot pass a Massachusetts inspection (if it is less than fifteen years old) if the readiness monitors are not set or if the Check Engine Light is on.

In many cars, the monitors can take as many as 100+ miles to reset. In addition, it may take several drive cycles for the monitors to clear. A drive cycle means the starting and stopping of the car’s engine, which gives it sufficient time to heat up and then cool down.

If your car fails inspection due to a Check Engine Light or insufficient resetting of monitors, a sixty-day grace period is granted so you can have the issue(s) resolved and pass a re-inspection.

Please feel free to ask us here at Greenfield Auto Specialists if you have any questions or are confused about the Check Engine Lights, readiness monitors, and state inspection rules. We’re here to help you in any way we can, and we’ll get your car back into tip-top condition!