The
Check Engine Light
A. What is the Check
Engine Light?
The “Check Engine
Light”
was originally named the “Malfunction
Indicator Light.”
Some
vehicles may have the words “Service
Engine Soon” instead of the “Check Engine Light.”
Self-Check- Once the ignition
key is turned to the “on” position
(engine off), all of the instrument panel lights should come on, including the
“Check Engine Light.” This checks the
bulb and diagnosis circuitry operation. The
Check Engine Light should go out (turn off) after about 10 seconds or
less. Once the vehicle starts, all of
the lights should turn off.
B. Purpose
The
purpose of the “Check Engine Light” is to alert the driver that an emission
control device on the vehicle is not operating correctly. If the malfunction is serious, that is, if
the engine is misfiring for example, the light may flash, otherwise it will
remain lit (on).
C. History
The
California Air Resources Board (CARB) required all new vehicles to have an
On-board Diagnosis system (OBDII) installed to monitor the proper operation of
emission control components. This
started with the 1996 model year and adopted by the US Environmental Protection
Agency to apply to all new vehicles sold in the US.
Requirements:
There
were specific requirements to meet OBDII standards, some were:
·
A
standardized connector located under the dashboard on the driver’s side of the
vehicle within 2 feet of the steering wheel (unless a waiver was granted.)
·
Vehicle manufacturers provide standardized
Diagnostic Trouble Codes (DTC) indicating a malfunction.
·
Devices
to control emissions is monitored and alert the driver if a malfunction is
detected by turning on a Malfunction Indicator Light (MIL) that is also known
as a “Check Engine Light.”
·
If
there is a malfunction, the OBD II system has the capability to store the fault
into the PCM (engine computer) memory for retrieval by a scan (diagnostic) tool.
·
After
a certain number of start cycles, if the fault does not continue, the check
engine light will turn off.
D. What to do if it comes on
·
If
the check engine light is flashing,
this indicates a failure of an emission control component or engine
misfire. If the vehicle drive ability is
normal, do not panic, just drive home and have it checked out as soon as
possible.
·
If you continue to
drive
with a flashing check engine light, the worst-case scenario is you may have to
replace your exhaust catalytic converter, which can cost over $1,000. If you converter needs to be replaced and you
cannot afford a new one, buy a used one from the automotive junk (salvage)
yard.
·
If the check engine
light is on steady
and the vehicle is running normally,
do not panic, just drive home and have it checked out as soon as possible.
·
If
the vehicle is not driving normally
but if it can be driven safely,
drive it home and have it checked out as soon as possible.
·
If
the vehicle is not driving normally
and cannot be driven, home safely,
have it repaired on location by a mobile mechanic (locate on internet or yellow
pages) or have it transported to a repair facility, preferably on a flatbed
transport truck.
E. Conclusion
The
Check Engine Light is not a diagnostic light to reveal internal engine damage
but rather to reveal faulty components that will effect emissions.
Therefore,
do not panic when the “Check Engine Light” comes on, it is only alerting you to
this reality. Three different vehicle
scenarios can occur when the check engine light comes on:
1.
The vehicle shuts off: Transport it to a repair facility.
2.
The vehicle runs
rough, has low power or runs bad: Drive the vehicle safely to the repair facility
or have it transported
3.
The vehicle drives
normal:
This is a less serious condition and a matter of a sensor malfunctioning or
something preventing a normal operating condition. Identify and correct the cause to prevent
damage to the catalytic converter.
For
Do-It-Yourselfers or willing to be DIY’ers, you can purchase an easy to use
check engine light reader with full instructions and systematic support from
this location http://www.carmd.com/
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topic: Is buying a certified used
vehicle worth it?
