CEL P0420
 

Could someone tell or show me where the sensors are?

And my car has been running hot, could this be part of it?

I have 2 P0420 codes when i checked it.

Pics or any help will be greatful

RE: CEL P0420
 

This trouble code is a couple of things:
An O2 sensor (either one in front of or the one behind the catalytic converter) isn't working properly
Bad coolant temp sensor
Damaged/Bad/Leaking exhaust manifold, catalytic converter, muffler(s)

Some suggested steps for troubleshooting a P0420 code include:
[ul][*]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 [/ul]
If it is heating up, you could have a plugged catalytic converter, but my bet would be a bad coolant temp sensor. That would be the cheapest way to go. (I believe) Good Luck!

RE: CEL P0420
 

I throw an occational p0420 code. I have a 3" downpipe and Magnaflow high flow cat. ZZPerformance also found a #4 cylinder misfire.
My guess is that you have lots of miles on the car. The code says catalytic convertor inneficiency. Bad cat's don't usually throw a code, but will affect performance SERIOUSLY! Shifting, also. It's not the temp sensor. ?????? Maybe a tune up is in store. I replace the coil for the #4 cylinder, and ordered the other 2 (FACTORY COILS ONLY!) Wires are next, if this doesn't help. I DO know my milage is now better.

RE: CEL P0420
 

P0420 code is the catalityc converter. What year is it? If it's an '01-'02, check this post https://montecarloforum.com/m_12459/tm.htm
That was the problem with mine.