“Why is my Check Engine Light On?”
The dreaded “Check Engine Light” (or “Service Engine Soon”) illuminates. What do you do and why is it on?
All modern vehicles have a computer or ECM (Electronic Control Module) that controls the engine operation. It also performs on-board diagnostics which are referred to as OBDII. The main purpose of this module is to keep the engine running at top efficiency with the lowest possible emissions. Today’s strict emission regulations are not very easy to achieve to keep it in compliance, the engine needs to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, gasoline quality, ambient air temperature, road conditions, etc.
Years ago a simple “Tune Up” would have fixed most issues causing the Check Engine Light to come on but due to the complexity of more modern cars, it’s best to let the professional staff at Precision Auto Repair properly test to find the root cause of the problem.
The best thing about the “Check Engine” light is that it often detects little problems before they become big, expensive problems. Not every problem gives you obvious indications like you get with such things as hard starting, rough running, stalling, etc. That’s why it is very important not to ignore this little light. The “Check Engine” light alerts you to problems like poor fuel mileage, reduced performance or excessive exhaust emissions.
What if My “Check Engine Light” is On?
The simplest way to handle this situation is to visit Precision Auto Repair where we will read the memory to see what fault the computer is reporting. Sometimes it is just a loose gas cap and other times further testing is required. We have all the equipment and information needed to determine and correct the problem. In the event the problem is something covered under the
manufacturer’s warranty, we will notify you so you can have it repaired at your dealer free of charge.
The Check Engine Light will also cause you to fail Mass State Inspection. Simply clearing this light without repairing it will also create a condition where the vehicle will fail State Inspection for Emissions. We will explain this in more detail in a minute.
“Service Engine Soon” Light
Since the “Service Engine Soon” Light is primarily an emissions monitor there is no need to panic. Unlike the overheat or charging system red warning lights that require an immediate shutdown of the engine, this one is advisory and is yellow or orange. Even though it doesn’t indicate the car is likely to quit, it is calling out for help. Think of the “Service Engine Soon” lamp as if it were the glowing tip of a cigarette. Your car is polluting as well as performing below its design potential. Plus, the average cigarette only burns for seven minutes and it is out, the car meanwhile will run for hours, days, weeks and even months.
Did a friend turn the light off only to have it come back on a few days later?
The on-board diagnostic (OBD) system is constantly performing a series of “self-tests” to determine if everything is working as designed and your car is running clean. When a failure is detected, the system will compensate if possible and many of these tests are temporarily turned off. This means the repair process can often lead down a trail of multiple problems. This is especially true if you have been driving with the check engine light on for several days.
Once repairs are completed, the OBD system re-starts its series of self-tests. Some of the self-tests require specific conditions to occur before they can be run. For example, one requires the engine to not be started for at least eight hours. Another requires the vehicle be driven for several minutes above 50 mph. This is why the testing phase is so critical to effecting a proper repair the first time.
Once all of these self tests have been completed the vehicle is ready for daily driving and Mass State Inspection.
Have a question about your Check Engine Light? Give us a call today or feel free to schedule an appointment online now. We’re happy to help.
You have options!!
Most Check Engine Light Diagnosis takes about 1 hour and we bill for that hour. But if you don’t want to pay for it we have 2 options for you.
- Precision Pride Club
- Allows you to get up to 1 hour of diagnosis totally FREE of charge or
- 5% off all Repairs and Services for life
- Quick 10
- This is a totally FREE 10 minute inspection to try and determine if the vehicle is safe to drive or not (This is what part stores do for free too, same thing)
- Please note: While we may be able to determine the failed part in 10 minutes on some vehicles, other vehicles will require proper diagnosis and about 1 hour of time.
A very friendly group of people. The waiting area is very neat and tidy as well as comfortable. Service time was as expected and no more than the price quoted at the time the appointment was made. I will gladly contact Precision again as my vehicle needs warrant it.
East Longmeadow, MA