Catalytic converter/O2 sensor issues

[landarcht]

My 2005 was recently diagnosed via the code scanner it's having cat. issues. The mechanic I usually goes to reset the lights and told me of they (check engine and two VSC lights)come on again, then for sure should be the cats and will determine which of the four cats need to be replaced. I hear this would be a very costly repair and need to be sure in fact are the cats.
Does the scanner pick up in case it could be the O2 sensors that's gone bad? I also heard there are two O2 sensors, one in back and one front. I really appreciate if I can get some insights into this before taking it in and get a major bill for this.

 

[Skolfoppa]

I would start by cleaning the MAF sensor. If the code pops back up move down the line. Toyota cats are strong imo, and I'd bet an o2 sensor would go first.

 

[letitfnrip]

The day after I bought my '07 LC I got a P0430 code. Was hoping it was the O2 sensor but the first shop I took it to said it was the cat and quoted me the OEM part at $1,600 plus almost $300 in labor. Land Cruiser Specialist here in Austin recommended I take it to his guy at Meineke for a second opinion.....they confirmed it was the cat and quoted me $400 total for an aftermarket part and labor.

Went the Meineke route, CEL light went off and the truck runs great. I know it won't last as long as the OEM cat but I didn't want to spend nearly $2k to fix it.

 

[AggieLC]

I went into the hood (yes the cars at the shop had spinners), and got a cat replaced for $150 parts and labor, no more lights or P0430 code. A shop charged me $1500 to replace a cat before so even it only last a year or two it's cheaper, with that said I'm a broke college kid and if I had the money I'd get the good stuff

 

[landarcht]

Did you guys replace one, two, or how many cats?
I hope it's the O2 sensors or cleaning of MAF.
I may go the chain muffler shop route if I can't find a reputable mechanics in the San Gabriel Valley area. Any recommendation would be appreciated.
I prefer the OEM-cost more up front but will last longer.

 

[mmaakk]

Here is the company I used to replace one drivers side cat. Great price and 1-1/2 yrs later still good. Straight bolt on which was great!

 

[marshotel]

The O2 sensors are the measuring devices that trigger the cat code. Each exhaust bank (left and right) has one O2 sensor before the cat and one O2 sensor after the cat. The O2 concentration should be lower after the exhaust has passed through the catalytic converter, compared to the pre-cat measurement. If the signal is the same before and after the cats, then it triggers the cat code in the system.

So, the cat code could be triggered by either bad cats, or bad O2 sensors. I think you can read the signal from each of the O2 sensors with a scanguage, or similar device. If you can figure out which exhaust bank is triggering the code, then you could swap the O2 sensors and see if the code moves to the other bank.

O2 sensors are far less expensive and easy to replace than the catalytic converters, so it makes sense to at least check the O2 sensors before replacing the catalytic converters.

That said, I replaced my factory catalytic converters with "canamex" high flow cats in stainless steel downpipes from "EMS powered" about 3 years ago, and they improved the performance of the truck and are still running fine under pretty harsh conditions (subzero temperatures and lots of short trips). I think "EMS powered" went out of business, but the point is that, if you need new cats, the aftermarket cats are just fine if they are installed properly.

https://forum.ih8mud.com/threads/100-series-cat-back-exhaust.617693/page-27#post-8680785

 

[landylover21]

I had a code pop up a few years ago (either P0420 or P0430, can't remember) and I replaced both downstream O2 sensors and it hasn't given me a problem for three years now.

Edit: I ended up replacing both upstream sensors as well due to my anal retentiveness.

 

[Sandroad]

There are 2 cats and 4 O2 sensors. On these trucks, the upstream sensors are usually the first to go. They live a hard life. Replace both upstream sensors with good Denso units and reset the CEL lights with a code reader. If the CEL is triggered again, replace both downstream sensors and reset. I'll bet that will fix the problem and you may get better mpg to boot. It's likely that only one O2 sensor is bad, but I recommend replacing them in pairs when one dies as preventative maintenance. Run some searches on cats and you'll see the LC cats are rugged and unlikely to fail.

 

[2001LC]

My 2005 was recently diagnosed via the code scanner it's having cat. issues. The mechanic I usually goes to reset the lights and told me of they (check engine and two VSC lights)come on again, then for sure should be the cats and will determine which of the four cats need to be replaced. I hear this would be a very costly repair and need to be sure in fact are the cats.
Does the scanner pick up in case it could be the O2 sensors that's gone bad? I also heard there are two O2 sensors, one in back and one front. I really appreciate if I can get some insights into this before taking it in and get a major bill for this.

I doubt your mechanic said 4 cats, if he did replace him.

First what was code(s)?

Does cabin heater blow very hot?
When was last minor tune up (air filter, PCV, vacuum hoses, T-body, MAF & battery cleaning, etc...)?
How many miles on odometer?

 

[beedo34]

I had p0420 and p0430 pop up after going cat-deep in the mud so I reset the lights and they came back a few weeks later. Gave the cats and the frame a good hose down and reset the lights and I'm all good about 6 weeks later. So maybe you have buildup around the cats or the sensors that could be causing this.

 

[re_guderian]

I doubt your mechanic said 4 cats, if he did replace him.

First what was code(s)?

Does cabin heater blow very hot?
When was last minor tune up (air filter, PCV, vacuum hoses, T-body, MAF & battery cleaning, etc...)?
How many miles on odometer?

Agreed, start with the code. Likely a P0420. I don't think there is a code specific to the catalytic converter itself, rather the entire system based on O2 sensor reading thresholds. Many likely root causes, and as mentioned here, the converter itself is rarely it (and conveniently for the shop, one of the more expensive and profitable ones to replace...)

 

[tacoduck]

There are 2 cats and 4 O2 sensors. On these trucks, the upstream sensors are usually the first to go. They live a hard life. Replace both upstream sensors with good Denso units and reset the CEL lights with a code reader. If the CEL is triggered again, replace both downstream sensors and reset. I'll bet that will fix the problem and you may get better mpg to boot. It's likely that only one O2 sensor is bad, but I recommend replacing them in pairs when one dies as preventative maintenance. Run some searches on cats and you'll see the LC cats are rugged and unlikely to fail.

THIS^ he nailed it... I hate throwing money at a problem... but in my experience, 15 year old o2 sensors need to be replaced. start with the upstream sensors.... if that doesn't work, jump to downstream sensors.

FYI- when I had CEL emmissions issues, once I swapped the o2 sensor, the light went off immediately. (i didn't have to drive it for a couple of days). Good luck!!!

 

[KYLandy]

Several of us are dealing with bad cats in this active thread:

P0420 and P0430 - 2006 LC

 

[landarcht]

So looks like I will start with the O2 sensors and see if that takes care of the Cat problem.

 

[TokenSki3r]

My 2005 was recently diagnosed via the code scanner it's having cat. issues. The mechanic I usually goes to reset the lights and told me of they (check engine and two VSC lights)come on again, then for sure should be the cats and will determine which of the four cats need to be replaced. I hear this would be a very costly repair and need to be sure in fact are the cats.
Does the scanner pick up in case it could be the O2 sensors that's gone bad? I also heard there are two O2 sensors, one in back and one front. I really appreciate if I can get some insights into this before taking it in and get a major bill for this.

OP says that along with the CEL, he has two two VSC lights on. Cats and O2 sensors wouldn't have anything to do with VSC, would they?

Curious because I am having the same issue with the CEL and two VSC lights. I know this has been discussed in the other thread, but my tech said the P0420/P0430 codes can come from running the truck at high elevation when its used to sea level or lower elevations. The truck also just passed CA smog, so it would be a coincidence for a cat or O2 sensor to fail a few days later.

 

[Sandroad]

OP says that along with the CEL, he has two two VSC lights on. Cats and O2 sensors wouldn't have anything to do with VSC, would they?

Curious because I am having the same issue with the CEL and two VSC lights. I know this has been discussed in the other thread, but my tech said the P0420/P0430 codes can come from running the truck at high elevation when its used to sea level or lower elevations. The truck also just passed CA smog, so it would be a coincidence for a cat or O2 sensor to fail a few days later.

I would go by the codes and not the dash lights. The combination of dash lights can be odd and others have posted that it seems Toyota software engineers turn on "extra" lights in some circumstances just to make sure drivers pay attention. For example, when the brake booster fails, pretty much the whole dash lights up.

 

[Sandroad]

Several of us are dealing with bad cats in this active thread:

P0420 and P0430 - 2006 LC

I just read through that thread and see only a couple posts on possibly bad cats, including yours. It apparently had a leaky rusted connector pipe? (It was hard to follow it all). Everything else was on O2 sensors or fuel system maintenance.

 

[KYLandy]

I just read through that thread and see only a couple posts on possibly bad cats, including yours. It apparently had a leaky rusted connector pipe? (It was hard to follow it all). Everything else was on O2 sensors or fuel system maintenance.

I haven't replaced the intermediate pipe yet, so I don't know if that will fix my issue. I still have the A/F sensors to replace, as well. My problem is still unresolved. I was never able to find a reason why the cats went bad because nothing exists now that would be ruining them, plus I have only owned the vehicle since October 2016. My guess is that the PO did a thermo quench on them. Apparently, driving through some really cold water or snow and cooling them down quickly can ruin them. That's my best guess, at this point, and the reason why I have not replaced the cats, yet. I want to make sure that they don't get ruined again if there is an existing issue. I posted a lot of Techstream photos on that thread and I have gone through every engine parameter in Techstream to make sure that there's nothing that could ruin new(ish) cats.

 

[KYLandy]

OP says that along with the CEL, he has two two VSC lights on. Cats and O2 sensors wouldn't have anything to do with VSC, would they?

Curious because I am having the same issue with the CEL and two VSC lights. I know this has been discussed in the other thread, but my tech said the P0420/P0430 codes can come from running the truck at high elevation when its used to sea level or lower elevations. The truck also just passed CA smog, so it would be a coincidence for a cat or O2 sensor to fail a few days later.

The computer has the capability to reduce engine power as part of the VSC system. If the engine isn't performing correctly (i.e. P0420/P0430 codes), then computer disables the VSC. I know, seems stupid, but that's the logic. I guess the engineers figured that the VSC system wouldn't respond well if there is a problem with the cats, which is true if they are clogged.