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Will a bad Catalytic Converter ruin my engine?

I have a 2002 Nissan Altima. It is on its second engine because I was an idiot and let it run hot (at least I think that’s why.)I’ve heard this make and model has a problem with the catalyst, and it can affect the engine. Others tell me it won’t I need a new catalytic converter, but I really don’t have the money right now. What will happen if I leave it be?

If the catalytic converter is partially restricted it can cause an engine to run hot.

How do you feel about having to replace the engine again?


$100 at Catco, some penetrating lube, and a wrench. Do the work yourself if you’re short on cash.

Unless it’s covered by a recall, there’s certainly no reason to replace it preemtively. The damage that tester describes will only come about after the check engine light has been on for some time. Can we assume you’ve learned your lesson about warning lights?

Is passing an emissions test an issue here??

No, not in Alabama.

When you say you let it run hot, do you mean the engine overheated because of a problem with the cooling system?

I hope you didn’t just replace the engine without solving your overheating issue. That happened to me once. I was given a car that had recently had a rebuilt engine installed. The engine had to be replaced because it had overheated, but nobody could figure out why it had overheated. Eventually, I figured out the passages in the radiator had become clogged and a new radiator solved the problem, but it could have cost me the rebuilt engine in the process if I hadn’t been careful.

I have had a clogged catalytic converter, and while it did make the exhaust manifold glow at night, the temperature gauge never changed and the warning light never came on. Is the “check engine” light on?

[i]If you haven’t already done so, you need to find out why your old engine overheated before you blow another engine.[/i]

Here’s the full story with the 02 through 05 Altimas.

Since the QR25DE motor doesn’t use an EGR system, it phases the intake and exhaust valves to lower the NOx temps.

The problem is, that this causes exhaust gasses to be sucked back into the combustion chamber from the exhaust manifold.

For a while, Nissan used a bad cat converter material, and as the miles piled on, the catalyst material would flake off the converter, and be sucked back into the combustion chamber, and slowly sand blast away at the cylinder walls, eventually increasing the bore size until the engine started consuming engine oil on an alarming level.

Some engines can suck down 2 quarts of oil in a week, driving on the highway, 50 miles each day, in some reported cases.

So, if the original engine was replaced with a new/manufactured one due to massive oil consumption issues, but the converter wasn’t replaced, it should be replaced TODAY. If the installed engine was a used one, with greater than 80k miles, compression and leak down tests should be done to determine the health of the replacement motor, and the converter replaced to prevent any further damage.


“No, not in Alabama.”

Passing third grade is not required in Alabama. :slight_smile:

Har Har. Like I haven’t heard that one before.