My check engine light is on with code 0420 - Catalytic Converter below threshold.
The funny thing is i just got a inspection sticker with no problem about 1 week earlier. I asked someone and they said the fault code for the catalytic converter may be caused by a Mass Airflow Sensor.. that is slightly out of range. Does anyone know what this could be.. any suggestions because i doubt i need a new catalytic converter if i just passed inspection. right... any help would be great

 

I had this issue before I cleared it by replacing my 2 O² sensors but i just got my inspection sticker last week and the p0420 code came back on so im going to try and change my cat hopefully under 250 bucks from the Acura dealer.

 

$250.. i thought it was real expensive especially at the acura dealer. i thought just the part alone is close to 1 grand... and does the cat come with the o2 sensors also.. thanks for the reply

 

The cat doesnt come with the o2 and you will also need the 2 gaskets for the cat im waiting for my buddy at the Acura dealer to get back to me on an exact price.

 

oh ok thanks- i guess nobody else knows anything about this code,... cmon im sure someone has some ideas... anymore info about the mas or the iat sensor.. does anyone think it could be those triggering the catalyst error... i just dont think it needs a whole new cat considering i just passed inspection. thanks again

 

My engine check light came up and for the same code right before I had to get a smog check. I did a ECU reset by disconnecting the battery and the light didn't turn on for another 600 miles. I passed smog but I was told that a new cat would be 700 bucks. Car runs great but the light is back on. Let me know what you guys have done since.