What Does My Check Engine Light (Service Engine Soon) Light Mean?
The Check Engine Light (CEL) is perhaps the least understood Malfunction Indicator Light. It is one of the most recently added warning lights (1980). It lights when there are no apparent symptoms. It is often perceived as being related to pollution controls only. Also, you may have been advised by someone else to ignore this light: we do not recommend ignoring this light.

Years ago, on-board computer systems weren’t very accurate and they had less direct control of the fuel and ignition systems. Today’s on-board computers are in total control of the fuel system and ignition system, processing about 60,000 pieces of information per second. Failures detected by the CEL no longer pertain to just pollution controls.

All engine sensors are part of a closed loop or feed-back system. When one part is on the fritz, it can cause problems for other sensors, the catalytic convertor – the expensive part(s) of the exhaust system, and even for internal engine parts such as piston rings and valves. Diagnosing a Check Engine Light immediately and addressing repairs can stop problems before they cascade into bigger problems.

Your On Board Computer – The Basics
Your vehicle’s computer is known as the Powertrain Control Module (PCM). As part of the architecture of the system, your vehicle is equipped with several electronic monitors inside the PCM. According to the Motorist Fact Sheet (available from the Department of Motor Vehicles), there are up to eleven possible monitors, but presently no vehicle has all eleven monitors. The number and type of monitors your vehicle has is determined by the manufacturer’s emission control strategy. The eleven possible monitors are:

Continuous Monitors: These three monitors are found on every gasoline OBDII vehicle.
1.) Misfire
2.) Fuel Trim
3.) Comprehensive Components

Non-Continuous Monitors: The following eight monitors are very different in design. Certain conditions must be met before a test or series of tests on a system can be completed by the PCM.
4.) Catalyst (CAT)
5.) Exhaust Gas Recirculation (EGR)
6.) Evaporative (EVAP)
7.) Oxygen (O2) Sensor
8.) Secondary Air
9.) Heated Catalyst
10.) Air Conditioning (AC) System
11.) O2 Sensor Heater

For the purposes of the emissions portion of the New York State Inspection, the readiness status of all supported, non-continuous monitors are only considered in making the OBD II pass or fail determination. For most gasoline-powered vehicles, this involves three to five monitors.

The CEL will come on if any of your vehicle’s equipped system monitors detect a failure. Each system is comprised of multiple parts; any of which may be involved in the malfunction. Therefore, proper diagnostics are required to determine the system(s) involved with setting the CEL, and to pinpoint which part(s) involved in the system(s) need to be replaced. Call Whalen Automotive at (518) 272-8601 immediately if your CEL is on.

A Flashing Check Engine Light Means Pull Over ASAP And Call For A Tow!
If your CEL is flashing (not solid), pull over and have it towed to Whalen Automotive immediately! A flashing CEL indicates that your engine is misfiring. Driving while your engine is misfiring can cause permanent engine damage. Whalen Automotive is AAA-Approved. We also have a secure key drop box outside the office, located at 1003 Ninth Avenue, Watervliet, New York.