hello!
I've searched on this issue and didn't really find anything so I'm hoping someone would have more insight on this. I got a the dreadful engine light and the code is P0430 Catalyst System Efficiency Below Threshold (Bank 2)
Anyone experienced this ? do I need a new catalytic converter? or o2 sensors? If it was the o2 sensors there are separate codes for that correct?? if anyone could shed some light I would appreciate it.

it's for a 2009 C300

 

no one has experienced this?
help!!

 

Did you ever resolve that Catalyst Efficiency code?

Are you ale to offer any insight as to what it was? O2 sensors? Bad Catalytic converter?... Possibly a vacuum leak?

 

These 420 and 430 codes are Errors for CAT efficiency below threshold. The fix is to replace bank 1 or bank 2 CAT, not O2 sensor. You may want to tap them lightly and reset the light. CATs are warranty for 8 years or 80k miles. Whichever one is first. As you are in LA, you will have to pay more for a CA certified CAT. Unless you know someone lived outside CA that the CAT can be shipped.

 

Thank you for your reply...

Interesting that you would post those codes as 420 and 430 because in that format, those appear to be MB-DTC codes that would correspond to a P0141 which is in turn defined as: "Heating of Component G3/6 (Right O2 Sensor, after TWC [KAT]): Heating Capacity Too Low (P0141)" and a P0057 which is defined as: "Heating of Component G3/5 (Left O2 Sensor, after TWC [KAT]) : Short Circuit To Ground (P0057)" respectively.

As for P0420 & P0430, and according to the OBD-II - Mercedes Benz DTC Cross Reference list that I have, those two codes are not defined for the W204 model I have. Instead, Catalytic Converter Efficiency Bellow Threshold for both Left & Right Banks (actually defined as "The efficiency of the right or left catalytic converter is insufficient (function chain) (P0422)") are reported under the P0422 OBD-II type code which in turn, corresponds to Mercedes Benz DTC Codes 942 & 946.

And in that context, O2 sensors are indeed a possible culprit. Especially considering the fact that using one code reader that is capable of displaying O2 sensor data, it is showing both pre-cat sensors at zero volts at a time when they should be fluctuating from Lean to Rich and back...