Engine Diagnostics

Engine Diagnostics

“Check Engine ” or “Service Engine Soon” light: Don’t hit the panic button, but don’t disregard it either.

It’s a small rectangle hidden among the gauges clustered on the instrument panel behind the steering wheel.  It flashes briefly when you turn on the ignition along with other system checks, like anti-lock brakes – to let you know the system is ready to perform its prescribed job.

After briefly flashing at start-up indicating all is well, it is blank and dormant as you drive happily on your way.  then one day, inexplicable it glows yellow and warns “Check Engine”.  What do you check and why?  The engine shows no signs of anything except running down the road.

The EPA and the California Air Resources Board established regulations requiring on-board diagnostics systems on cars and light duty trucks.

All 1996 and newer cars and trucks have a powerful computer which uses second generation on board diagnostic or OBDII technology.The purpose of the OBDII system is to ensure proper emission control system operation for the vehicle’s lifetime by monitoring emission related components and systems for deterioration and malfunction. .  When the OBDII system determines than an emission problem exists, the computer illuminates the dashboard light indicating “Service Engine Soon” or Check engine light.  this light usually yellow in color, servicies to inform the driver that a problem has been detected and vehicle service is needed.

It assesses engine misfire situations, the most severe of which indicates the possibility that the catalytic convertor is in danger of overheating.  When this occurs, the yellow “check engine” light will flash.

The vehicle should not be driven long distances with the light flashing.  This can mean many things, from an oxygen sensor to a fouled spark plug.  This is more of an immediate concern.

If the light stays on and does not flash, , this is not an emergency situation, but it should be checked at your earliest convenience. A common cause is a loose gas cap. Check to make sure it is tightened properly.  After tightening, the light may go off after a few trips.   This is not an indication of a faulty system.  In fact, the system is doing its job to verify that a problem existed and was caused by a temporary problem which has gone away.