Topic 'catalytic converter? P0420' in forum 'Automotive' - dslreports.com

Re: catalytic converter? P0420

Wed, 13 Feb 2013 09:29:54 EDT

Gordo74 posted :

I Tired Premium fuel and the code went away. That was for the long trip.

Tired with mid-grade fuel again code came back. interesting. $75 worth of fuel down the drain. I think the PCM was tunned for Premium fuel. Huge possibility. since it had 5 previous owners.

I just going to use up the tank and filler up with Premium chevron fuel.

If it has a tuned PCM, it WILL need premium fuel.

I would contact Miltzy motorsports (most likely the ones who tuned it) and see if they will send you a stock one aback in exchange for your tuned one.

Re: catalytic converter? P0420

Wed, 13 Feb 2013 02:32:23 EDT

gillespie posted : Interesting, you might want to take it to the stealership and have the factory tune put back in and go from there.

Re: catalytic converter? P0420

Tue, 12 Feb 2013 22:32:28 EDT

Anonymous_ posted : I Tired Premium fuel and the code went away. That was for the long trip.

Tired with mid-grade fuel again code came back. interesting. $75 worth of fuel down the drain. I think the PCM was tunned for Premium fuel. Huge possibility. since it had 5 previous owners.

I just going to use up the tank and filler up with Premium chevron fuel.

Re: catalytic converter? P0420

Thu, 07 Feb 2013 02:18:08 EDT

gillespie posted : Bet me! Bought it at a place called the Muffler warehouse in Ashland. $90 out the door. It's a universal heavy duty cat. Has lasted over 90k with not even a hint of a problem.
03 Grand AM 3.4L.

Re: catalytic converter? P0420

Wed, 06 Feb 2013 19:33:12 EDT

TA63 posted :

said by gillespie:

I would agree if you get it at a big chain store, but they make high quality aftermarket cats that perform just as good if not better than the factory cat.

Not a chance. Not for anywhere near $90.00, that is for sure.
--
The talented hawk speaks French.

Re: catalytic converter? P0420

Wed, 06 Feb 2013 11:01:57 EDT

gillespie posted : I would agree if you get it at a big chain store, but they make high quality aftermarket cats that perform just as good if not better than the factory cat.

Re: catalytic converter? P0420

Wed, 06 Feb 2013 04:20:39 EDT

anon posted : This is California we are talking about here. A aftermarket CAT is not sufficient enough for our tough standards. :(

Re: catalytic converter? P0420

Wed, 06 Feb 2013 03:52:00 EDT

gillespie posted :

said by Anonymous_:

going to get it fixed but later this year when it's time to smog.

FACTORY replacement is required to pass.

otherwise getting a after market is throwing money into a money pit.

Not true. IIRC Fed. law states that you must have a converter installed. It doesn't state anywhere that it has to be factory.
As far as an aftermarket converter, I got one from a place that only does exhaust. I got a heavy duty universal converter and installed it myself. That was roughly 90k miles ago and haven't had a lick of trouble. Now having said that, I strongly discourage you from getting one from Autozone or Advance auto parts. I guarantee you 'll have problems. BTW the converter only cost $90 out the door.

Re: catalytic converter? P0420

Tue, 05 Feb 2013 20:27:57 EDT

Anonymous_ posted :

said by TA63:

If that cooling system is clean, then I am a monkey's uncle.

By the way, did you ever get that cat dent out of your fender?

Yeah but it left a ruffle in the metal/paint
Now I having issue with the land owners dogs jumping on my car.
but if they damage it he has to pay for it or get it fixed, no more free passes.

Yes the coolant is Clear pink in color in the radiator.
I mix my own coolant 50/50mix

since premixed 50/50 is a scam , the non mixed makes 2 gallons for the price of one gallon 50/50mix.

50%/50% mix=12.99
100% coolant is 13.99 +1 gallon distilled water =0.99cents =14.99

=16.39 including sales tax

2 gallons of 50/50 is 29.42 including sales tax

since you are paying for only 50% of the coolant and the rest is water.

this comes out to paying 13.03 for just water and a bottle.

Re: catalytic converter? P0420

Tue, 05 Feb 2013 19:36:05 EDT

TA63 posted : If that cooling system is clean, then I am a monkey's uncle.

By the way, did you ever get that cat dent out of your fender?
--
The talented hawk speaks French.

Re: catalytic converter? P0240

Tue, 05 Feb 2013 19:03:33 EDT

Anonymous_ posted :

said by Gordo74:

What does the radiator cap have to do with the issue at hand? A good cleaning of it would have been fine rather than replacing it.

And you bought a thermostat just because they only had a few left in stock? You realize places like rockauto.com are cheaper and ship to your door, yes? Why buy something when you don't need it?

For someone who complains so much about how the car "costs you too much" (other thread), you sure do love throwing needless money at it.

Thermostat is going to be returned as the new cap fixed the issue.
If you see the rubber seal is torn and cracked .
That probably means it has a poor seal on it.

Car sits at the under the middle line even with the a/c on full blast.

Yes rocketauto is great but if you need the item by tomorrow it will cost the same or more to get it.

Re: catalytic converter? P0240

Tue, 05 Feb 2013 08:23:26 EDT

Gordo74 posted : What does the radiator cap have to do with the issue at hand? A good cleaning of it would have been fine rather than replacing it.

And you bought a thermostat just because they only had a few left in stock? You realize places like rockauto.com are cheaper and ship to your door, yes? Why buy something when you don't need it?

For someone who complains so much about how the car "costs you too much" (other thread), you sure do love throwing needless money at it.

Re: catalytic converter? P0240

Tue, 05 Feb 2013 00:50:33 EDT

Anonymous_ posted :

said by rockotman:

said by TA63:

said by Anonymous_:

that was the fuel regulator

That killed the cat.

I thought curiosity killed the cat. :p

I mentioned a failed cat that I experienced above. The dealer service manager at the dealer thought that a failed ignition module that I had experienced a few months earlier which turned my 4-cylinder into a 2-cylinder on Christmas day the previous year may have lead to my premature cat failure.

As I loaded the family into the car on Christmas day to go visit relatives, the car ran extremely rough, so I parked it and we all jumped into my son's Scion to go visit family. I can tell you that 6'1" does not fit well in the back of a tC. ;)

Anyway, the next day I dropped my "2-cylinder" off at the dealer (1 mile from the house) to get it fixed under warranty. It was, as I suspected, the ignition module. It was dumping raw fuel into the exhaust for only about the 5 or 10 minutes it took to get to the dealer. But the following March, the cat failed.

replaced the radiator cap as it had caked on dirt preventing it from working correctly. I got a thermostat as well but I have not installed it Only got it because they only had a few left in stock.

coolant is clean so it does not need to be changed

Re: catalytic converter? P0240

Mon, 04 Feb 2013 20:31:23 EDT

rockotman posted :

said by TA63:

said by Anonymous_:

that was the fuel regulator

That killed the cat.

Re: catalytic converter? P0240

Mon, 04 Feb 2013 20:17:52 EDT

TA63 posted :

said by Anonymous_:

that was the fuel regulator

That killed the cat.
--
The talented hawk speaks French.

Re: catalytic converter? P0240

Mon, 04 Feb 2013 03:40:25 EDT

Anonymous_ posted : that was the fuel regulator

Re: catalytic converter? P0240

Sun, 03 Feb 2013 22:55:51 EDT

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

Re: catalytic converter? P0240

Sun, 03 Feb 2013 21:06:30 EDT

Anonymous_ posted :

said by rockotman:

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

100% "clear" air comes from the tail pipe. a lot of it
before I was getting 22-23mpg highway

Now gas mileage shot up was getting 35MPG (300miles round trip total) (computer claimed 45MPG average though.)
80 to 99 (inst mpg)

Re: catalytic converter? P0240

Sun, 03 Feb 2013 21:04:21 EDT

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

Re: catalytic converter? P0240

Sun, 03 Feb 2013 20:57:50 EDT

Anonymous_ posted :

said by TA63:

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.

Thanks the light went off, after I smacked the catalytic converter, with a rubber mallet. :D
saved $1400 doing that. 150miles+ no light

Now I have to deal with the thermostat... since it's overheating now, to keep it under the 1/2 point I drove it 150 miles with the heater on and windows & moon roof open)

coolent is full maybe it has some air in the system or thermostat is failing ?

yes it has coolant in it

Re: catalytic converter? P0240

Sun, 03 Feb 2013 16:53:36 EDT

Formeister posted : 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.

Re: catalytic converter? P0240

Fri, 01 Feb 2013 19:42:28 EDT

TA63 posted : 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.

Re: catalytic converter? P0240

Fri, 01 Feb 2013 12:33:55 EDT

Anonymous_ posted : 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

Re: catalytic converter? P0240

Fri, 01 Feb 2013 09:19:53 EDT

Gordo74 posted :

said by TA63:

said by Gordo74:

P0420 on my Impala ended up being that there was a vacuum leak in the system near the gas tank. A tube came loose is all.

That makes no sense. Perhaps you have misremembered your code?

I never said it made sense, but repairing the vacuum leak made it go away and MPG returned to normal.

Re: catalytic converter? P0420

Fri, 01 Feb 2013 08:42:20 EDT

telco_mtl posted :

said by Anonymous_:

going to get it fixed but later this year when it's time to smog.

FACTORY replacement is required to pass.

otherwise getting a after market is throwing money into a money pit.

just curious, where are you? can you get a used one from a jurisdiction that doesnt have rules about selling used cat's

Re: catalytic converter? P0420

Fri, 01 Feb 2013 05:40:26 EDT

Formeister posted :

said by Anonymous_:

I think the o2 sensor needs replacement because of the fuel regulator issue ,cause it to get "dirty" due to the rich mixture.

I've heard that rich mixtures will cause cats to overheat and kill them.

Re: catalytic converter? P0420

Fri, 01 Feb 2013 00:46:30 EDT

rockotman posted : How many miles on the car? By federal law, cats are required to be covered for 8 years/80K miles on cars from 1995 and later.
--
Shine on you crazy diamond...

Re: catalytic converter? P0420

Fri, 01 Feb 2013 00:38:00 EDT

Anonymous_ posted : going to get it fixed but later this year when it's time to smog.

FACTORY replacement is required to pass.

otherwise getting a after market is throwing money into a money pit.
--
Well, does your car at least turn into something else? Sometimes I turn it into a trashcan. Hmm...

Re: catalytic converter? P0420

Fri, 01 Feb 2013 00:19:29 EDT

rockotman posted : I have had a P0420 code once. It was indeed a failed converter. Luckily, the converter was still under warranty.
--
Shine on you crazy diamond...

Re: catalytic converter? P0240

Thu, 31 Jan 2013 23:57:52 EDT

telco_mtl posted :

said by mattmag:

said by Anonymous_:

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

What makes you think that? Your assumption in this case is wrong. P0420 is very often a stand-alone code, and requires no other associated failures to enable it.

exactly, like i just posted, faulty cats threw that code on my both grand prix. same car as the impala, and those were the only codes i had

Re: catalytic converter? P0420

Thu, 31 Jan 2013 23:56:38 EDT

telco_mtl posted :

said by Anonymous_:

getting a new issue

catalytic converter code P0420

P0420 Catalyst System Efficiency Below Threshold (bank1)

I think the o2 sensor needs replacement because of the fuel regulator issue ,cause it to get "dirty" due to the rich mixture.

Not worried about passing smog since that is 9 months away

I had it reset to see if it comes back on maybe just a fluke.
Not getting any smoke out of the rear end tail pipe.

Please no tree hugger crap in this thread .

i bought a 02 grand prix with a hollowed out cat and it was throwing this code, my 97 grand prix also threw it. replacing the cat fixed it.

Re: catalytic converter? P0420

Thu, 31 Jan 2013 23:54:40 EDT

bgraham posted : The OP would be wise to listen to the advice of mattmag. I too decided against paying $1200 for the OEM Buick cat and went to Rockauto and paid $200. Exactly a week after the 12 mos warranty expired I started getting a PO420 about every other week. Googled the problem and there is a lot of issues with PO420 and cheap replacement cats. Replacing the cat is the only answer.

I will add that I replaced the original OEM cat at 100k miles due to it being blocked.

Re: catalytic converter? P0240

Thu, 31 Jan 2013 23:21:38 EDT

Anonymous_ posted :

said by mattmag:

said by Anonymous_:

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

You were behind a smoking bus *twice* to make it come on? You said you already had the code cleared once. And, that's a virtually impossible scenario to cause that code anyway.

What sensor do you plan on replacing on a blind guess? Upstream or downstream? I really don't understand why people want to come up with every reason under the sun why this code sets. There is a converter failure code so you want to replace the oxygen sensor. If a code sets for an cylinder #4 misfire, are you going to replace a headlamp?

I'm being straight here--- BOTH related-bank oxygen sensors MUST BE operating properly for this failure code to occur. The computer is measuring exhaust oxygen content BOTH before AND after the catalyst to determine its efficiency. A malfunctioning O2 sensor strictly prevents this diagnostic cycle from running, and will set a SENSOR failure code, NOT a catalyst code. There are no "false positives" here.

I will add that the best course of repair is proper diagnosis. Get the system tested, preferably by a shop that can scope the components to get the correct picture. Like I said, very high percentage its the converter. Oxygen sensor failure is very rare.

I'll just wait tell I need to do the smog test (you bet I going to clear the code before I get the test done)

if it passes then it's a faulty SENSOR. if it fails I get it fixed
--
Well, does your car at least turn into something else? Sometimes I turn it into a trashcan. Hmm...

Re: catalytic converter? P0240

Thu, 31 Jan 2013 22:39:38 EDT

mattmag posted :

said by Anonymous_:

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

Re: catalytic converter? P0240

Thu, 31 Jan 2013 22:26:04 EDT

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

Re: catalytic converter? P0240

Thu, 31 Jan 2013 22:24:03 EDT

mattmag posted :

said by Anonymous_:

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

What makes you think that? Your assumption in this case is wrong. P0420 is very often a stand-alone code, and requires no other associated failures to enable it.

Re: catalytic converter? P0240

Thu, 31 Jan 2013 22:21:42 EDT

Anonymous_ posted : 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

Re: catalytic converter? P0240

Thu, 31 Jan 2013 20:45:06 EDT

TA63 posted :

said by Gordo74:

P0420 on my Impala ended up being that there was a vacuum leak in the system near the gas tank. A tube came loose is all.

That makes no sense. Perhaps you have misremembered your code?
--
The talented hawk speaks French.

Re: catalytic converter? P0240

Thu, 31 Jan 2013 16:01:28 EDT

Gordo74 posted : P0420 on my Impala ended up being that there was a vacuum leak in the system near the gas tank. A tube came loose is all.

Re: catalytic converter? P0240

Thu, 31 Jan 2013 13:41:58 EDT

mattmag posted :
That's funny, because the first reply I typed "P0420" then realized it didn't match his post and changed it. Guess my subliminal memory should have been obeyed. ;)

Re: catalytic converter? P0240

Thu, 31 Jan 2013 12:40:27 EDT

cdru posted : Is the error P0240, or P0420? Catalyst system efficiency below threshold is P0420 although it seems that dyslexia on the internet is very common and they get flipped.

I'd visually inspect things to make sure that there isn't any damage to the O2 wiring harness, make sure the plug(s) are tight, etc as well as make sure there aren't any exhaust leaks, reset the code, and go from there.

Re: catalytic converter? P0240

Thu, 31 Jan 2013 09:54:38 EDT

mattmag posted :

99% of the time, a P0420 means you need to replace the deficient converter. O2 sensor failure *will not* cause the P0420 to set, but rather will give sensor failure codes. Monitoring the catalyst efficiency requires both the upstream and downstream sensors to be properly operating, so it is generally a very accurate failure code.

Nothing wrong with clearing it and seeing if it comes back, that's prudent.

EDIT: Dyslexia.....lol

Re: catalytic converter? P0240

Thu, 31 Jan 2013 09:48:07 EDT

jsouth posted : Could be.I wouldhavea shop place it on a scanner to narrow it down. My code turned out to be a bad egr valve.

catalytic converter? P0420

Thu, 31 Jan 2013 09:22:33 EDT

Anonymous_ posted : getting a new issue

catalytic converter code P0420

P0420 Catalyst System Efficiency Below Threshold (bank1)

I think the o2 sensor needs replacement because of the fuel regulator issue ,cause it to get "dirty" due to the rich mixture.

Not worried about passing smog since that is 9 months away

I had it reset to see if it comes back on maybe just a fluke.
Not getting any smoke out of the rear end tail pipe.

Please no tree hugger crap in this thread .