My catalytic converter on 2010 CRV has had check engine light on since 90K miles, it now has 103K miles. Problem is getting worse with fuel consumption and hesitation while driving. I am trying to get prices on a new catalytic converter, but in doing research, I found out that catalytic converters were designed to last the life of the car, and something is causing the issue, either ignition system or fuel system. The repair garage just tells me to get a new catalytic converter, but the blogs I read say the problem will only return if the source of the cat failure is not discovered. Can anyone help me? Catalytic converters are expensive to replace. It's the upstream part, near the motor.

 

While true - the problem could return if the root issue is not addressed, it could just be a maintenance issue like spark plugs. Or aging upstream O2 sensor. Or Intake/exhaust valve lash clearances.

On the other hand it could be worn piston rings, or valve stem seals, or worn valves/seats allowing oil into the combustion chamber, running rich and clogging the cat. These scenarios are kind of unlikely for a Honda at 100k unless it’s been neglected.

If this were my vehicle, I would get the catalytic converter replaced, both O2 sensors, spark plugs and valve lash adjustment done.


How much are they charging you for the replacement?

 

Spark plugs have already been replaced. I hate to shoot in the dark replacing everything and then the problem remains...it might not be O2 sensor, and they are costly and frustrating if the problem is going to remain. Is there any way to get a diagnosis of the fuel system and ignition system. I've had other problems with the ignition, and I read somewhere on a blog that ignitions can cause the problem. But, to replace the cat without going to the source...the problem is going to return. I read that cats don't just fail, something causes them to fail. Question - how do I find out, rather than trial and error replacing other parts that might not be bad?

 

Hook it up to a good scanner and check the o2 voltages.

 

What ignition problems have you had?
When were the spark plugs replaced? Did they come gapped? Did you have your intake and especially exhaust valve clearances checked and/or adjusted while doing the plugs?

Like the other guy stated - you'll need to hook up a scan tool and check the O2 voltages to see if one or both is failing. If voltage fluctuates wildly then the sensor you're looking at is probably bad.
You could have your ignition coils checked, I believe all you can do is test resistance - i've never had to test one tbh.
You could have your fuel pump (and lines) tested for pressure and volume. Compare these values to OE specification.
Also test your fuel injectors, make sure they aren't hanging open/closed or having some strange electrical malfunction.
You could do a leak down test which would indicate if a valve/rings/gasket is leaking. Love this test - it can tell you a lot.
You could check your timing and make sure it hasn't jumped a small amount. Although I would suspect that would throw a camshaft position code or something similar. Some of these others ones would probably set a code as well.

There's also the possibility that the catalytic converter actually did go bad. I've replaced cats on vehicles that are around 9-10 years old and they didn't come back. I did always replace the O2 sensors though.

Or if you really don't want to put in all this work, and depending on your state/locality: remove the cat from the vehicle and gut it out with a prybar and hammer. Clean out all the broken pieces. Reinstall the empty pipe. You'll prob get MPG back and less hesitation. It'll stink nasty though.