Check engine light

[Tom H.]

I have a 1989 Lincoln Mark VII and for sometime now the check enging light
blinks on and off...I've been told this has to do with the smog equipment
and would like to find out what needs replacing. The engine runs great and I
have not noticed the gas mileage getting worse...

[Scott Chamberlain]

The check engine light is connected to a number of sensors throughout the
engine. When one of the sensors sends out an incorrect reading, this causes
the check engine light to come on. The incorrect reading is caused by one of
two things: Either there is actually something wrong with the engine OR the
sensor is bad. For instance, if the oxygen sensor reads that the engine is
running rich (too much fuel), the cause could be that the engine is indeed
running too rich and needs something like a fuel pressure regulator. OR, the
engine is running just fine, but the oxygen sensor itself has gone bad.
Either of these conditions would send an incorrect reading to the computer
which turns on the light. The only way to tell for sure what is causing the
problem is for you to take your car to a local mechanic where he will attach
a code scanner to the car which will display a code. By using the code, the
mechanic can determine what is wrong, be that a faulty sensor or a very
badly running engine.
Tom H. wrote in message ...