Q: How to remove and install Fuel Injector and Fuel Rail on Hyundai Sonata?A: Replacing injector O-rings is recommended even if only one is leaking to avoid future issues. For 2010 and earlier models, after relieving fuel pressure and disconnecting the battery cable, removal involves disconnecting injectors' electrical connectors, removing the fuel rail assembly, replacing O-rings and grommets if reusing injectors, then reassembling. For 2011 and later models, the intake manifold is removed, high-pressure fuel pipe disconnected, injectors' electrical connectors and fuel rail pressure sensor disconnected, fuel rail mounting bolts removed, retaining clips for each injector removed, and upper O-rings discarded. Injector installation requires thorough cleaning, lubing new upper O-rings with oil, cleaning injector bores, inserting injectors into fuel rail, tightening new fuel rail mounting bolts, and reassembling. In both cases, Teflon sealing rings can be installed with special tools or by fitting onto a socket and using plastic tubing for shrinkage. Careful attention is needed to avoid damaging components.