Ok so my check engine light is on, do we check the code it reads p0420 which is catalac converter. Now when those go there's usually a raw egg smell. I don't smell anything so I googled the code and it said o2 sensor could be the problem. Now I think we have 4 o2 sensors. I have a awd 2006 gs 300. I ask the guy at a local shop and he said it should be the o2 sensor on the cat because if it was a different one then it would read a different code. Is this true because I called the dealer and I'm bit going to pay $135 just for them to look at it. Or could it be something else that's throwing the code?

 

That should be it, why not replace it yourself and save the labor time to look it over. Hit up our vendor Sewell Lexus and order a new sensor and call it a day.

 

P0420 Catalyst Efficiency Below Threshold.

1. Check for exhaust leaks
2. Bad post Oxygen Sensor
3. Last defective Cat.
-Get a rubber mallet and lightly tap if Cats are rattling, if yes, it will need to be replaced.
-Get a pyrometer check the temperature of the inlet and the outlet, the outlet should be hotter than the inlet. If not, replace Cat.

Good Luck

 

Ive been getting the same error code, 2 indy mechanics told me its the cats, I was a lil skeptical so I decided to take it to dealer and see, turns out its just an exhaust leak which is covered by fed mandate,and they are replacing it

 

One of the first things someone should always check with a P0420 error code, is the MAF (mass air flow) sensor and the air filter. The MAF gets dirty and needs to be cleaned with MAF sensor cleaner or an electronic cleaner. I usually use a q-tip also. If the MAF is dirty with a dirty air filter is will also set a P0420 code. Its a lot cheaper to clean the MAF and check the air filter, as opposed to replacing a CAT or O2 sensor.