Honda Jazz fuel injectors get dirty over time. When this happens, you can clean them or replace them. Since cleaning them tends to be impractical for most people (you need to have them cleaned for you), many people simply replace the injectors. When you notice your Jazz start to hesitate at low RPM, or stall at idle (or if you experience a rough idle), then you need to remove the injectors and decide if you want to clean or replace them.
Relieve fuel pressure by removing the fuse for the fuel pump. Pull down on the fuse panel cover under the steering wheel, and locate the fuel pump fuse. Use the diagram on the underside of the fuse panel to locate the fuel pump fuse. Pull the fuse using the fuse puller in the fuse box. Start the engine and wait for the engine to stall. The fuel pressure has been relieved at this point.
Disconnect the negative cable running to the battery. Loosen the nut on the cable clamp running to the negative battery terminal, and slide the clamp off the terminal.
Remove the air cleaner assembly. Remove the bolts that hold the air cleaner to the body of the Jazz. Loosen the screw on the hose clamp with a screwdriver. Then, slide the hose clamp off the end of the intake tubing, and pull the intake and air cleaner assembly off the throttle body.
Remove the bolts holding the intake manifold to the engine. Remove the intake manifold to exhaust manifold bolts. Remove the intake manifold.
Disconnect the electrical plugs that run to the fuel injectors (which are now visible with the manifold removed). Then, remove the harness crip from the fuel rail assembly.
Pull back on the quick-connect slide connector, and pull the fuel injector fittings off the fuel injectors.
Pull the fuel rail bracket off the fuel rail. Unbolt and remove the fuel rail mounting nuts. Pull the injector clip off of the injector.
Pull the fuel injector off the fuel rail.