06 Civic, Bad Catalytic Converter?

[houdini1313]

Hi all,

Daily driver is an 06 Civic, 249k miles. I’ve taken regular care of it, very few issues in general. Replaced a starter, a few batteries, and the usual brakes and tires.

Check engine light is on, and showing the code P0420 for Cat not performing to standards. There has been an engine rattle from time to time, no changes in mileage or loss of power.

The car is worth 1,500 if everything was good, but obviously has needed repairs. I wont pay an insane repair bill for it (dealership said 1,700 ) Honestly any large repair is likely not worth it.

What would you do in this situation? How much life can I expect? Starting to look at used civics 2014-17, anything in those years to avoid?

Thank you!

 

[JC1]

Dealership will be the most expensive option. You can buy an aftermarket cat for probably less than $300. The dealerships objective is to fix and not offer you the best option for your budget and age of car etc. Find a muffler shop if you cannot DIY this repair.

Does Indiana require emissions tests? I would just reset it with a code reader and see how long it takes to come back in the meanwhile.
It could be that the Cat wasn't warm because it was a really cold day or something temp related.

I had a 98 Sienna with that condition. I would reset the cat and then it would stay off for a while before coming back.

Reset the code and watch it for a period of time and maybe when it trips that code observe the outside temp it is happening at. If your car is running well otherwise, I would look at the cheapest options to replace the cat if needed.

 

[skyactiv]

You could simply keep driving it.

 

[houdini1313]

Indiana does not require emissions tests. I’m worried about how long it will last, and if it gets more symptoms (loss of power, worse gas mileage).

 

[mk378]

You can keep driving. The only effect of the cat being worn out and throwing P0420 is that the car is making more pollution than it should. But it is not going to affect performance or lead to a breakdown.

 

[Blinker]

Sounds like a good candidate for an aftermarket cat.

 

[97prizm]

Sometimes other issues are underlying causing problems. Is it possible that the O2 sensors are going bad as well causing an issue? If you hear rattling it's possible that the honeycomb inside the catalytic converter has been damaged leading to either it spitting pieces out, or plugging up which isn't good.

 

[pezzy84]

Indiana does not require emissions tests. I’m worried about how long it will last, and if it gets more symptoms (loss of power, worse gas mileage).

Worse gas mileage is a strong possibility. I may be wrong but I think most ECM's default to closed loop mode when check engine comes on and fuel/air ratio sticks to stoichiometric (14.7) as a protection envelope for the powertrain.

Loss of power - seems your cat just reached end of useful life, its probably flowing fine but just not reducing measured emissions enough to satisfy the downstream sensor.

 

[houdini1313]

Thanks for the replies and info everyone! If I find an aftermarket cat should I also replace O2 sensors? Trying to put as little money into it as is 250k ~ $1500 if it was running well (which it is besides the cat issue). I was planning on saving up for another good slightly used civic soon anyway, would prefer to pay for it in cash (Dave Ramsey style).

 

[ctechbob]

Like others have said. P0420 won't cause any issues other than the cat not working up to spec. The only thing I would watch out for is the cat breaking up and clogging the exhaust. This could be the rattle you're hearing. You can usually check this by smacking the cat with your hand and listening for a rattle. If it does, its breaking up.

 

[simple_gifts]

I had a p0420 on my echo. I replaced the O2s and that got me maybe 1.5 years; the next time it came up I did a manifold back exhaust replacement.

Eastern Catalytic has some nice aftermarket cats; "Nice" in the fact that there were no problems installing it; it was a no hassle bolt on process.

 

[555]

If the cat is falling apart and pieces go flying out the exhaust pipe,you're ok. If the pieces obstruct flow in the exhaust pipe or worse in the cat,heat will create issues especially in warmer months that will be problematic.

 

[houdini1313]

Like others have said. P0420 won't cause any issues other than the cat not working up to spec. The only thing I would watch out for is the cat breaking up and clogging the exhaust. This could be the rattle you're hearing. You can usually check this by smacking the cat with your hand and listening for a rattle. If it does, its breaking up.

The rattle is not all the time, just occasionally when idling, and occasionally when accelerating.

 

[Chris Meutsch]

I drove a 2001 Civic to 227k. I got that same code. Reset light, keep driving, zero issues.

 

[gathermewool]

Have you reset the ECU to clear the code? It may not come back for a long time.

Rattles can be anything from endlinks to tensioners to to mounts, to heat shields, etc.

I believe these have timing chains, right?

 

[Vercingetorix]

Try an O2 spacer.

 

[2010Civic]

I'd consider a O2 defouler.

 

[slacktide_bitog]

249k isn't bad for a cat on those cars

The 8th gen Civic actually had problems with the cat, and many were replaced under warranty (federal law requires 8 years/80k on a new OEM cat)

You can get a converter for $200 on Rock Auto, or $100 on eBay. It obviously won't last 249k, but you can get another year or two out of it. You should also replace the oxygen sensors along with it. Denso and NGK/NTK are the best brands to get.

The 9th gen Civic went from 2012-2015, basically just a facelifted 8th gen; the only meaningful changes were for the Si model. It lost the 8000 rpm K20 for a K24. 2016 is when the new Civic came along. They have lots of problems with the turbo, so don't get a 1.5T Civic!

However, the used car market right now is crazy, and Hondas, especially Civics, don't depreciate much even without the problems now. An aftermarket cat should last long enough to ride out the pandemic and let the used car market cool down again.

You might be able to get a new Mirage for the price of a used Civic

 

[Wolf359]

What engine is the car? Rockauto carries converters, depending on the engine, they're $250-$400. You could replace the upstream oxygen sensor also, but those are about $100. You could try clearing the code and seeing if it comes back. But a 420 code usually means that both sensors have the same reading which means that the cat isn't doing anything. The upstream one normally gets worn out first. I believe aftermarket cats typically have a 5 year/50k warranty so while they're not as good as an OEM that will last 250k, getting 50k out of it wouldn't be too bad.

 

[atikovi]

Indiana does not require emissions tests. I’m worried about how long it will last, and if it gets more symptoms (loss of power, worse gas mileage).

Most DIY owners of $1500 cars in such states would just gut the cat if they get more of those symptoms.