The Honda Civic was originally introduced as a three-door hatchback. The 2004 Honda Civic was available in two-door, four-door and hatchback versions, with models that included the DX, EX, LX, HX, GX, Hybrid and Si. Two main engines were used in the 2004 Civic: a 1.7-liter SOHC four-cylinder, and a 1.7-liter VTEC four-cylinder. Both engines have the same location for the exhaust gas recirculation valve. Not much can be done in the way of repairing the EGR valve, except cleaning the valve body. The new EGR valve costs around US$125 as of the time of publication.
Raise the hood on the Civic and set the hood prop.
Remove the electrical harness from the the top of the EGR valve, which is located on the front passenger side of the engine. The EGR sits right next to the engine cover and the air intake baffle, behind the radiator.
Remove the two mounting bolts from the EGR valve, using a ratchet, socket and extension. Turn the bolts counterclockwise to remove them from the engine. Pull the EGR valve upward and out of the engine completely.
Inspect the bottom portion of the EGR valve. There is a small orifice at the bottom of the valve. If this orifice is completely blackened with carbon, you can try to spray Sea Foam or throttle body cleaner into the orifice. If spraying the EGR with cleaner shows no sign of removing the black carbon inside the EGR, then replace the EGR valve completely.
Install the EGR onto the engine, placing a fresh gasket between the EGR and the engine. Tighten the bolts snug with a ratchet and socket, then turn the ratchet 1/4 turn farther. The EGR valve is not a moving part, so not much torque is needed to hold it in place. Over-tightening the EGR valve bolts can break the mounting tabs on the valve. Attach the electrical connector to the top of the EGR valve.
