1998 Honda CRV engine light still on.

Hi Kellie,

P0420 = Catalyst efficiency below threshold. Possibly the catalytic converter is faulty or there are leakages.

P0304 is cylinder #4 misfiring whereas P1399 is a temporary code for the misfiring.

I would suggest checking th EGR system as it affects the # 4 cylinder.

Updated 3-12-10
Ok, what is the EGR system? What do I need to tell the mechanic? Is this expensive, dangerous or a nuissance?

Its the exhaust gas recirculation its job is to recyle the unburn gas back to the engine to get a 2nd time burn and reduces the combustion chamber temperature to prevent detonation/pinging.

Could be diluting the A/F mix leaning it out-meaning more air than fuel to burn that's causing misfires.

I recommend you have the sparkplug, compression and injector for no.4 checked out to knock out the P0304

Also for the catalytic converter could be unurned fuel, oil, oxygen and coolant temperature sensor problem.

Back to the EGR system

Labor on it is 1/2hr and EGR valve is about $s30.00 USD total costs varies with locations-could be $70.00-$130.00 per hr on labor-