I've had a chipped ecu running perfectly for several weeks, chipped it myself and ran with no check engine lights. The other day I got a solid check engine light (code 0) and I don't know why. I didn't change anything, didn't install anything, didn't tweak anything.

The solid CEL only appears when running off a chip. running it from stock gives me no check engine lights. I've check all of my connections visually and with a multimeter. They all check out fine. what would cause this check engine light to come up so suddenly while the car still runs PERFECTLY fine, no hiccups what so ever?

 

If you don't have a rev limit at 3500 it's not in limp mode as a solid cel would suggest.

 

What code(s) are being stored on the ECU, a solid CEL does not always mean a code 0. If you have the SCS connector jumpered/shorted with a wire/paperclip and the CEL is solid that means that there are no codes. A solid CEL while your driving just means that there is a stored diagnostic trouble code(s) on the ECU. Retrieve the code(s) and see what it says.

My guess would be that maybe the check sum has not been removed or it is an issue with the circuits that have been modified on the ECU. aka the chipped part.

 

It revs fine and everything... no limp mode. With the key in the on position i jumped the connector on the passenger side under the glove box area and the check engine light just stays solid. I guess it could be the chipped part, but i think it's weird that it would just come on out of no where after reading the chip perfectly fine for quite some time, and still continue to read the chip fine even after it throws the code

 

Reburn the map to see just to see if the file is corrupted. Or go through all your soldering again.

 

Ok, so jumping it has a solid cel... is there a cel when it's not jumped? If not then whatever code came up that lead you to check in the first place has been erased and there's no codes currently. If so maybe you have an improperly setup CEL shift light feature.