U0302 Honda Prelude is described as Oxygen Sensor Circuit No Activity Detected (Bank 1, Sensor 1). This means there's a problem in the front oxygen sensor on Bank 1, as the O2 sensor is inactive. As you drive and when specific conditions are slowly met, the vapors will gradually purge from the charcoal canister and will get burned within your engine.
Possible Causes :
If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs. Look at the plug wires to make sure they are not burnt or laying on the exhaust. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.
Diagnostic trouble code U0302 Honda Prelude is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.
Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before U0302 Honda Prelude.
Fortunately, U0302 Honda Prelude is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.