Just purchased a 2004 Accord EX and had issues driving home. Took the car to my mechanic and there were four error codes that came up but the Check Engine light never came on. Bottom line, the previous owner some how disabled the Check Engine light and now it will not come on at all, no matter what. My mechanic pulled the instrument cluster but found that the lamp is an actual LED. Is there a way to replace this lamp or is there some other way to get it working again?

 

I assume the driver's under-dash Fuse No. 21 (7.5A) fuse and yellow power wire leading to the Gauge Control Module (instrument gauge) is okay, as it sounds like every other indicator lights up on the module?

Check to see if the Check Engine Light LED solder points are making contact with the Printed Circuit Board (PCB) and the LED. The previous owner could have just de-soldered a contact point along the path to the Check Engine Light LED, such as at the LED or the resistor leading to the LED (there should be a resistor along the path to that LED on the PCB). Extreme case, would be the previous owner cut a trace along the path, still repairable; but, easy for him to just de-solder a contact point along the path.

If the solder contacts appear okay, then check whether the LED is really blown, by applying very low voltage (using a resistor with adequate resistance to limit the voltage) directly at the LED contacts or apply power before the resistor on the PCB if you can identify the correct resistor on the board. You have to apply power and ground to the correct contacts; otherwise, you can burn out the LED or something else, the same as applying too much voltage.