Technical > Automotive > catalytic converter? P0420

reply to Anonymous_

Re: catalytic converter? P0240

yeah it was p0420 got it rechecked had two entries on it. going to change out the sensor first to see if it fixes that. Since it's way cheaper then paying $1200 to replace it with a factory catalytic converter

New state law requires factory down to the exact model and production code. Other wise automatic fail.

If it was the catalytic converter I would be getting more codes besides the P0420

CEL was tripped when behind a diesel bus that was pouring out smoke.. assuming it was sucking craptastic air from the truck which caused it to trip .

and caused higher emissions from the car = CEL

I was behind a bus that was pouring out a lot of smoke, when the CEL came on.

reply to mattmag

reply to TA63

mileage is sloppy been getting 18MPG city(@near highway speeds 45-65mph ) and 23MPG on the freeway.(very hilly though)

before the fuel regulator went out I was getting 17/22
when the fuel regulator was dead 9MPG/15MPG
(No visible smoke with the "rich mixture")

Not getting any visible smoke from the tail pipe.
using 1 qt of oil every 2,000-2100 miles which is at manufacture specification.

I use 89 octane fuel
engine runs quieter over all with this fuel.

engine Is running warmer then normal (but still with in the normal accepted rage aka the middle)

But I think it still should be less since it is winter and is fairly cold outside mid 40's

Ones in bold might be the possible issue

A code P0420 may mean that one or more of the following has happened:
Leaded fuel was used where unleaded was called for

A damaged or failed oxygen sensor (HO2S)
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
Retarded spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure

Cylinder misfire
Oil contamination

That is a funny list. I googled it, and in the first hit it seems to have been posted in the comments on an Amazon sale for an O2 sensor.

The second link, »www.obd-codes.com/p0420 , has these 2 gems:
"Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily.

We strongly recommend that if you need to replace the catalytic converter that you replace it with an OEM unit."

Go ahead and replace that sensor if you want. It isn't my money you are burning.
--
The talented hawk speaks French.

P0420 Catalytic efficiency below threshold value.

My daughter's 1998 Accord threw this code twice, about two years apart. The first time I guessed and didn't test the 02 sensor, just replaced the easiest sensor to reach, the one after the cat and code cleared. Two years later, same code. Naturally, I replaced the inlet O2 sensor this time. Code cleared. Car sold three years later with original cat and 240K miles.

The cat converter efficiency can only be measured by two O2 sensors: in and out.

So, I would test each O2 sensor as they are so easy to remove, before I'd spend a bunch on a new cat.

BTW, there are thermal tests that can be done on a cat to determine if it's functioning correctly but most home owners don't usually have the thermocouple sensors and meters.

Cats do fail, I've just never seen it on many high (>200K mile) cars that I have driven, ymmv.

reply to TA63

Hmmm.... a clogged cat can also cause excessive back-pressure which can lead to overheating.

Hmmm .. p0420 and a rough idle.
»03 impala idle issues
2 + 2 = 4

that was the fuel regulator