How can i check if my "check engine light" system works?

Question

i just bough a car the swap the engine and I'm don't think this system is working how do i know? i got an 03 civic si

Answer 1

If you replaced the engine with another size, you'll probably be replacing a lot more then that because the computer in the cars are "matched" to the factory engine that was installed.  You'll probably have to buy a computer as well as additional wiring harnesses.  Might be more money than what its worth.

Edit to additional info:

Since you say the check engine light does not come on during bulb check, the PCM is not receiving power on one or more data lines.  Better retrace every wire imaginable or if worse comes to worse, remove the engine and check for any pinched or chaffed wires.

Answer 2

I'm assuming you bought the car with a swapped engine.  Make sure the bulb is actually there.  Remove the cluster and look.  I have seen engine swaps with constantly "on" check engine lights due to incompatibility or a damaged system causing the CEL to illuminate.  The owner removed the bulb to make it look like the car was 'ok'.  

Could even be a burned out bulb.  Unplug the IAT or TP sensor and turn the key on.  Those components are easily accessable and will set a DTC immediately.  Could be easier that removing the cluster, if you can clear the DTC afterwards.  

Answer 3

when you put the key in the ignition, the dash will illuminate the check engine light, this is a self test of the system when the vehicle is started, the light should go out, this finishes the self test. If problems were detected, the check engine light would remain on. If in doubt, have the system scanned for history codes and live data. If you can retrieve this, the system is working as it was designed.  

Answer 4

Don't bother fixing it. Too complicated with a different engine installed. It's not worth it. If you have state inspections that require it to work, you're going to fail anyway because of the swap.  

Answer 5

when you start the car watch for the check engine light to light up while the system does a self check of the system.it will then turn off

Answer 6

Easiest way: Unplug one of the o2 sensors,the light should come on within 30-40 Min's. of driving,plug back in...It will take several days to clear the light,the computer has to see no faults in the system to clear.