2002 Corolla Catalytic Conver Gone Bad Twice - Toyota Corolla, Chevy Prizm (1998-2008)

Hello,

I have a 2002 toyota corolla CE with 92,000 miles on it..

4 months back itself Catalytic Conver has been replaced as it produced the P0420 code. Again the CEL is on with the P0420 code.

When i took it to the autocare they are saying that Catalytic Converter is gone. I am just wondering that some thing else is causing the issue, if the Catlytic conveter is gone.

I am just wondering that how to start the Diagnosis.

I have observed that its drinking excessive engine oil.

Could you guys please help on this.

Kumar.

149 posts

Using excess oil will kill a catalytic converter. You will have to fix the oil burning problem before replacing the cat again.

Hello,

I have a 2002 toyota corolla CE with 92,000 miles on it..
4 months back itself Catalytic Conver has been replaced as it produced the P0420 code. Again the CEL is on with the P0420 code.
When i took it to the autocare they are saying that Catalytic Converter is gone. I am just wondering that some thing else is causing the issue, if the Catlytic conveter is gone.
I am just wondering that how to start the Diagnosis.
I have observed that its drinking excessive engine oil.
Could you guys please help on this.
Kumar.

Your 2002 CE is a 3 speed auto or manual?

How much oil are you burning? 'Excessive' means different things to different people, and its pretty vague either way.

Any other symptoms besides oil consumption? Such as hesitation, problems starting, rough idle, stalling, or ticking/knocking or other engine noise?

Any evidence of oil burn through the exhaust, such as black carbon deposits around the tail pipe?

-Spyder

Thanks you very much for reply.

My car is 2002 CE is a 3 speed auto .

After oil change, oil been dried for 2000 mles. later i stated to add oil, i guess i used 1Q for a week(i.e for 250 to 300 miles).

There is no other complaints...i can say its giving milage 28 miles only.

I could see that black carbon deposits around the tail pipe .

Please let me know if i missed any thing.

You should never let the oil drop too much - check the dipstick regularly. Even dropping a quart, approximately from the "full" to the "low" mark on the dip stick, can be too much. The engine only holds 4 quarts of oil - if you regularly see no oil at all on the dipstick, could be looking at an expensive rebuild in the future.

Also, the P0420 code can point to many other systems. Even though the P0420 description is "Catalyst System Efficiency Below Threshold", very rarely on this generation of Corolla is the catalytic converter actually defective. About 70%-80% of the time - this indicates a faulty or damaged post-cat O2 sensor problem.

Oil consumption at the rate of a quart every 250-300 miles is quite excessive. As mentioned above, excessive oil consumption is fouling the catalytic converter, should try and address the oil consumption soon than later - otherwise the issues you are seeing will likely never go away.

Could u plz suggest me what might be the reason for consuming excess engine oil??

Could u plz suggest me what might be the reason for consuming excess engine oil??

Defect in the construction of the engine + relatively poor maintenance. Key word relatively.

I should add that over the past 6 months I have decreased engine oil consumption from 1 qt./200-300 miles to 1/2 qt. / 400 miles using Valvoline MaxLife synthetic blend 5w-30. I did a regular change in December and topped it up several times in the intervening months. Last top up before I changed the oil/filter today lasted 450 miles and oil was just below halfway down the fill marks. Hadn't seen this little consumption in years.

All I had at the house for today's oil change was Castrol GTX High Mileage 5w-30. We'll see if the consumption stays down.

Castrol GTX High Mileage is pretty decent oil too. Probably will not yield as impressive results as Valvoline MaxLife - but better than some others out there on the market.

sr100101 - can try shortening the oil change interval and use a high mileage oil / synthetic blends to see what is does for oil consumption. At the rate you are consuming oil - you are very close to the point of no return. Once oil consumption drops into a quart to 100 - 200 mile range, no amount of additives and/or oil combinations will fix that. Running on little to no oil really hurts too (increases rate of oil consumption) - so keep an eye on the oil levels.

Some owners have had results with AutoRx - reported that it helps to break up deposits that cause "stuck" piston rings, the most likely cause of oil consumption in the 8th gen Corollas. I'd also suggest that you look into a compression test on the engine. If compression is too weak or varies too much from cylinder to cylinder - this could be grounds to start looking for deciding how much money you want to pump into the car to fix it or start looking for another car.

so is it better idea to change catalytic conveter till oil consumtion come down.

Depends on the situation. Ideally, you want to fix the oil consumption first, or at the very least, try and slow it down. If you don't, you'll end up fouling another catalytic converter fairly quickly. If this code is causing the car to not pass emissions, then you should address the catalytic converter first, then address the oil consumption.

As I mentioned above - make sure that it is a bad catalytic converter before you replace it. The P0420 code is often misdiagnosed as a failed catalytic converter, when usually it is something completely unrelated.