One night i was driving, and my check engine light came on. I had 4 cel's (6, 10, 15, 21). I reset the ecu, and drove for another week. Then exactly a week later going to the same place with the same friend, the same thing happened. Now i know what these codes are, and maybe they are somewhat related because i think getting 4 at once is quite unusual.
The codes are 6-coolant temperature, 10- intake air temperature, 15- ignition output signal, 21-vtec solenoid.
What could be causing all of these to pop at once? I haven't had a code on the car in months now....

 

That is odd that all those codes popped up at once, it makes me think that its a wiring issue. Check all the wiring and the grounds.

 

IF i reset the ecu, i can drive around for about an hour, until they pop back on..

 

I would check those preticular wires and follow them from the sensor to the ECU and see if your grounding out anywhere... Seems to be a wiring issue. There is a chance that it could be the ECU...

Blaze

 

Oh yeah, its a 89 crx si with a b16a

 

I connected a loose part of the ground going from the headlight housing to the valve cover, one of the leads was loose.... Reset the ecu and drove around for a bit, and only the cel 21 popped back up? Other than checking the voltage and wiring, is there any other things to check? Never had this code before...

 

I'd say your ECU is bad. You had 2 temperature codes, and I figure after an hour of driving, the coolant and IAT reaches a certain point... well first off, the sensors tell the ECU numbers by different amounts of ohms or volts or something, and maybe the coolant and IAT levels are just too much for a cold solder or something. It sounds retarded, but you may at least want to check it out. Borrow someone else's ECU for a while or something.

 

Nevermind, I see you found at least A problem. I never seem to finish threads....