I've got an 03 Civic SI. It failed to start the other day with no spark or fuel at the injectors. The pump turned on and I heard the main relay click. The battery seemed strong but I charged it overnight. The next morning I disconnected and reconnected the negative cable and it fired right up.

Later that day, it was dead again. I had the battery tested and got the immobilizer brake code from the dealer. It didn't work. I checked all fuses and they were good. I tried the valet key. Unlike other immobilizer problems that I've researched, there isn't a flashing key light in the cluster, it never lights up period. It did light up when it started that one time. I thought it might be the transponder at the ignition switch, but if that was the case I would think the brake code would have still worked. I know everything mechanical is fine because it randomly worked the other day. Any ideas where to go from here?

 

Well, it works again... I just pulled the transponder out, popped the case open, tapped on the circuit board and it all works. Probably a bad solder joint in there, so a replacement transponder should fix it for good. I wish the dealer could disable these immobilizers, no one wants to steal this piece of junk anyway.