Honda '94 Accord LX fails CO% emission test readings! Help!?

I changed the air filter, oil, oil filter, and I am about to change the fuel filter, PCV, Spark Plugs and wires (these were last changes 1-1.5 yrs. ago), and PROBABLY the Cat Converter (I don't know how to do it, but I imagine it is not extremely hard, is it?) Here are the readings for both Virginia emission tests:



@ 15 mph:

HC ppm: Limit: 125; Reading: 20; Result: PASS

CO% : Limit: 0.50; Reading: .73; Result: FAIL

NO ppm: Limit 1636; Reading: 376; Result: PASS

RPM: Reading: 1777; Result: VALID

Dilution: Reading 14.7; Result: VALID



@ 25mph:

HC ppm: Limit: 136; Reading: 44; Result: PASS

CO%: Limit .73; Reading: .73; Result: PASS

NO ppm: Limit: 1591; Reading: 282; Result: PASS

RPM: Reading: 1802; Result: VALID

Dilution: Reading: 14.8; Result: VALID



Someone said I must change the cat. Any suggestions?Honda '94 Accord LX fails CO% emission test readings! Help!?Okay based on your HC and NO levels, the catalytic converter is probably okay, but there is not enough oxygen (O2) in the exhaust to convert the CO to CO2.



As mentioned - sounds like the O2 sensor is not properly talking to the computer. The O2 sensor and temperature sensor are two entirely different sensors. The O2 is in the exhaust stream and measure Oxygen concentration in the exhaust. The temperature sensor measures coolant temperature.Honda '94 Accord LX fails CO% emission test readings! Help!?Find someone with an engine code reader to find the problem.

If you can't do that then be sure the gas cap gasket is OK. Then replace th O2 Sensor before you do anything else.

make a video smaller

submit case after