I just bought a 2001 civic lx that the guy had swapped a vtec engine into using the lx harness and ecu. Seems to run fine but I want to know if is ok without the other components being used(vtec) etc?? Twice at around 5k rpms I've had a cel pop on for tdc sensor which threw it into limp mode. Cleared code both times and runs fine otherwise. Except the second time the battery light popped on and has stayed on.. Is the sensor cel coming from being the vtec engine? Or otherwise I believe it's from a semi clogged cat(per emissions test)

 

The engine swap should be fine.

A bad TDC sensor/circuit would throw it into limp mode. Diagnose the TDC sensor/circuit first.

 

Thanks laz, what's the best way to go about that? In 1000 miles of owning its happened twice. Like I said, both times under full throttle passing somebody at 5k rpms both times.