P0430 - Goes away after highway drive

[GremlinMobile]

I've been driving with this P0430 - Catalyst System Efficiency Below Threshold (Bank 2) code for over 6 months now. Tried 2 bottles of catakleen to no avail. My daily commute is a fairly slow 30-45mph drive with plenty of traffic lights. I have noticed that every time I go on a 45-60 min drive on the highway with speecs >55 mph, the check engine light goes away. For example, yesterday I drove on the highway for a total of 1.5 hours there and back, and the code is gone.

Is this a symptom of anything?

Any suggestions?

I read about people taking their catalytic converters off to clean them with all sorts of homemade potions. I'm afraid it's going to be so rusted that once I touch the nuts, everything will snap off. How doable is it to take it off to clean it?

I was thinking of trying the spacer method. Should get the O2 sensor far enough away to be happy, but I'm concerned that maybe the car's performance will still be degraded if the converter isn't doing it's job. Can that be?

 

[excessive]

Cats need to be at a certain temperature to work properly, maybe that has something to do with it?

 

[Trunk Monkey]

Have you tried replacing the O2 sensor?

 

[menancyandsam]

Some internet dudes claim putting a gal of laqcure thinner in 1/2 a tank and drive 150 miles will clean the cat and fix the code.
I've been thinking hard if I should try it.

 

[GremlinMobile]

Have you tried replacing the O2 sensor?

Well earlier last year I had an O2 sensor code on the upstream side which I replaced. That didn't seam to fix the issue. In my case, would it be the downstream sensor that might be bad? Is there something I can look at in techstream to see if the sensors are reading correctly?

If it's the downstream sensor, would swapping the right and left sensors be a good way to see if the problem bank follow the problem sensor?

 

[JZ100swamper]

I don’t have the answer to checking / diagnosis with tech stream, but I can share what I did before concluding I needed to declare my CATs finished/clogged . so far I’m glad codes gone.

- first code was one upstream O2 ( right). Replaced , code gone , passed emissions ( Dec 2022)

Then : approx 15 months ( spring summer 24 later Cat codes tripped again and by this time I had ordered the remaining 3 O2 sensors ( denso $62- $68 apiece) . Experienced long time Toyota mechanic said it’s prob the cats clogged … too much corn ethanol residue.

when
underneath the vehicle inspecting the downstream ….(. you mentioned rust , ) well the bung / tailpipe mount for downstream that receives the downstream sensors , behind the cat has a flange to receive the diamond shaped sensor gasket / washer , mine was corroded away …. It was also fairly apparent that the treads would be corroded and in fact , attempting to remove the old downstream sensors was likely going to snap off / break the tailpipe bung .

I went to a muffler shop that welds , and they replaced both downstream tailpipe bungs. (welded a repair section in that comes with the bung ) .

welding repair both sides, with parts cost of repair sections , screw in all three sensors $ 380 .

No CEL no codes returned since cleared . ( it’s only been about 3 weeks)

Amount half the cost of one cat magnaflow part only .

if one orig O2 sensor failed , the others can’t be far behind after 20+ years .

Lots of smarter folks than me have great cat posts here . (Personally the u tube spacer approach struck me as a stab in the dark for another vehicle that just needs to get registered one more time , not a solution for our special breed of cruisers )

Hope this helps . Please post any other concurrent codes you have , especially related to fuel vapor system)

PS : Menacy ….. Good gracious, man ! Don’t be tempted by the magic potion .. ever spend any time working with lacquer thinner and you’ll know what I mean… just think about how it has to travel to get to your CAT one wud think there’s a whole lot of expensive stuff it’s gotta pass by to get burned and into your exhaust that it can be good for)