I had an E63 error code that calls for heater failure. Went in and checked the heater with my meter. Everything looked ok but the E63 error code kept popping up. Took the heater apart and found that the metal support warped and caused the heating element to just barely touch the outside shell causing a short to the board.
See the heater coil just barely touching the metal shell? That's what caused the E63 error code.
Side by side comparison with a new unit on the right.So now you know!