shenminda

My 2007 GL450's CEL went on a couple of days ago, I bought a OBDII scanner and read the code is P0420, this should be something concerns about the Three way catalyst converter. But the CEL was gone two days ago and never comes again, but the code still can be detected by OBD scanner. Do I still need to do something? what is the major cause of P0420?

thanks

alx

It could be many things. Bad gas for example.

If it comes back again you should have it checked. Check your oil level (overfilled oil will trigger that error) and if ok- eave it alone for now.

shenminda

Appreciate for your information. I checked by OBDII scanner, the code P0420 still there even the CEL was already gone, So I have to do nothing except the CEL comes again right?

alx

correct. the code is stored, but currently not present. when condition is not currently present for x number of ignition cycles the "check engine" light will turn off for that particular code/ condition.

in other words - transient condition. hence my suggestion that due to it disappearing on its own it might have been caused by bad gas.

if it illuminates again- it could be a bunch of things.

shenminda

Thank you.

the CEL was not come again during these days. thanks again