1999 Acura Integra check engine light code P0420

JOSH01

MEMBER
1999 ACURA INTEGRA
4 CYL
2WD
MANUAL
16,000 MILES

I have the problem with the check engine light come on 3 times. First time was about 12/?/07 then 5/23/08 again on 7/18/08 then today 9/17/08. Every time it came on I had to disconnect the battery, then check engine light went off.
Now if I took my car to get inspection will the code P0420 show up to inspector? Or it will show up as nothing, so I can the pass inspection.
It seem that light came on every two month? Why? Could it be my catalytic converter bad or o2 sensor go bad? Why it have to be every two month it show up or just coincident.
And yes last 2 times was same code P0420.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

A code P0420 may mean that one or more of the following has happened:

Leaded fuel was used where unleaded was called for
An oxygen sensor is not reading (functioning) properly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Possible SolutionsSome suggested steps for troubleshooting a P0420 code include:

Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2), replace if necessary
Replace the catalytic converter