Burning or Leaking oil? P0420 code - Cat issues?

Was it at Full right after the oil change? You can’t know how much oil was in the engine before your trip - unless you check.


You said you added 2.5 to 3 Quarts of oil after the trip ,but in another post you said that the engine shows a quart lower that if you let it sit overnight. That means you were only 1 1/2-2 quarts low and that is not usually enough to damage the engine.

Unless you checked the oil level the morning after the oil change, you don’t know if they put in the right amount.

Higher speeds also may burn more oil on some cars. On trips, I check my oil when I get gas. About 500 miles on my Camry.

I’m not sure if it was at full right after the oil change. I wasn’t in the habit of checking my oil at this time.

The only reason why i checked my oil this time was because the oil light started to flicker when I hit the brake pedal. This is how I noticed the dry dipstick.

The dipstick actually showed more oil when I let the car sit overnight and less when I checked 10 minutes after turning the car off.

Yes, I’m hoping that the loss of oil was just due to it burning from driving at high speeds during my long distance trip. I definitely was going way past the speed limits for a significant amount of the trip. I’m not sure how likely this is though since my check engine light is on and I’m getting code P0420.

Car complaints only had 1 complaint for excessive oil consumption for the 2005 Camry

1 Like

Hey, guys. I really appreciate everyone’s help here.

I checked the oil again this morning and noticed that the oil is actually high. It looks like it’s even reaching onto the metal rod. I guess I’m just going to get an oil change to prevent this from creating further damage to the engine.

When I first noticed the dry dipstick after my long distance trip I added 2.5-3 quarts of oil. I believe this was done properly because I did the readings in the morning before turning the car on.

A week later I added about another quart. This was due to me getting a faulty reading of the oil after the car was running for a while.

Unfortunately, I didn’t start tracking the mileage after I added the 3 quarts, but I know for sure that I have drove about 500 miles atleast so far without losing a significant amount of oil.

I’m gonna double check on a possible leak soon with a piece of cardboard.

Thank you for this info.

Even though a leak like that is hard to miss, I really wasnt looking under my car when I took stops during my long distance trip.

I surely don’t have a leak that bad when I look under the car now though.

Can a leak be exacerbated during a long distance trip?

I read that engines tend to burn more oil when driving high speeds. I was driving very fast during my trip. If all the oil I lost is from burning, is it normal for all of this oil to be burned up during a high speed long distance trip? Or is it not normal, and does it definitely mean there’s significant damage to the engine?

how many miles were on the oil change when you started the trip? I have noticed over the years that vehicles with many miles on the oil tend to thin out and increase oil consumption.

A quart of oil per 1000 miles is considered normal nowadays, however 2.5-3 quarts seems excessive.
Maybe drop the catalytic converter and take a look inside and see if oil is making it into the catalyst.//

Very few miles were on the oil change before the trip. I basially got the oil change and started the trip right away.

Is it possible that 1 quart was burned from high speed long distance driving and the remaining 1.5-2 quarts leaked out with the nickel sized drops that I may be having every night? I started the trip about December 7th, and didnt notice the dry dipstick until about January 15th.

Nick , without an complete diagnostic it may still be impossible to answer those questions. Just make it a routine to check the oil once a week before starting the vehicle . If it shows a little usage just add oil and drive on . And just be glad your driving over the speed limit was not through Oklahoma where you would have been stopped by our over zealous Highway Patrol and have your car torn apart looking for drugs.


If the loss of oil is coming from a leak, from burning, or both, what do you think is the best course of action to get rid of the P0420 code?

The cat is fairly new and only has 20k miles on it.

Is there still hope for this car?

The car won’t pass emissions inspection in the state I’m in with a CEL.

Toyota Camry P0420: Catalyst System Efficiency → Below Threshold → Bank 1 | Drivetrain Resource (700r4transmissionhq.com)

just a thought… I had a power steering pressure switch go bad and was leaking fluid. the wind from driving blew the fluid onto and in the o2 sensor connector causing that code. you may have an oil leak doing the same. it is something easy to check.

1 Like

The very low miles vs the age of the car along with the oil change regimen can have an effect on oil usage.
Running the oil level low just makes a bad situation worse as the remaining oil will break down easier; leaking to sludging and/or coking.

The oil leak should be checked to make sure that it’s not due to a pressure port; as in oil filter, oil pressure sending unit, etc. That could mean oil usage may be worse than thought.

Given the code, cat replacement, etc odds are it’s burning most of it and it’s only going to get worse as the burned oil will cake up on the converter substrate. Think honeycomb with half of the cells clogged.

1 Like

Since you paid for an engine replacement, which still is under warranty, I would make the trip back to where you had the work done, and have the problem resolved under this warranty–presumably by replacing this junkyard engine with a different junkyard engine. If that is not possible, then it sounds like you are going to need to purchase new catalytic converters to install temporarily when it’s time for emissions testing, and then remove them and reinstall the defective ones for general usage.

1 Like

It does not take very much of an oil leak to make a pretty decent mess. I’m inclined to think that most of your oil loss is through consumption within the cylinder, which would be worse with higher rpm. And it would foul your catalytic converter, which even though is new-ish, would not have the longevity of an OEM unit.

I can’t speculate as to why you’re burning oil in an engine model that’s not known for it, but its treatment by the previous owner who needed to send it to the junkyard might have something to do with it.

You should clean up what you can and search for the source of that leak too. But I think you’re mostly burning oil and that problem could require a ring job to correct. Hopefully the warranty will come through.

1 Like

P0420 can be many other issues as well.

Found this for the code P0420 code

Gives a description of all the causes and things that may be the issue. The P0420 code that you are noticing may be from another issue all together.

I think all 70k junkyard motors have more mileage then stated.



The 2AZ-FE was known to use a lot of engine oil

What is a ring job?