Catalytic converter
 

Hey, CL. I'm fairly new to the forum, and so far I have really enjoyed being a member! About 3 weeks ago I picked up an '03 Gs300. My first Lexus, and I have loved so much. Yesterday after driving about 70 miles of interstate, my CEL, VSC and VSC 'off' lights all came on at once. Pulled the code and got: P0430 Catalyst System Efficiency Below Threshold (bank 2)
P0430 Catalyst System Efficiency Below Threshold (bank 2)

When the lights came on the car did not feel any different, and I didn't hear anything out of the norm. The only other driving issue I've noticed since owning the car is that when I'm driving in stop and go traffic or coming to a stop the car has a little stutter or jerk right before the vehicle comes to a complete stop.

I was going to let my tank drain and run 93 and sea foam. But let me know what you guys think! If it is a catalytic converter I was wondering if I could buy a universal Magnaflow? Thanks in advance!

search... there are plenty of threads on here about this topic...

first thing you need to check for is an exhaust leak at the flange of where you header meets the exhaust before the cat...

Before you go throwing on a new converter, you may think about changing the downstream O2 sensor. They can cause the same code to get thrown.
http://www.obd-codes.com/p0430

First step is check for exhaust leaks like kamlung said.

This code is for Bank 2 so you only need to concentrate on that bank

How many miles do you have?

Seafoam is the last think I would put in a car with a CAT and O2 sensors. It is over 50% oil with a little Naptha and Isopropyl alcohol. It is snake oil...only thing it will do is lighten your wallet.

You should already be using 93 octane, although using lower wouldn't cause your issue.

I'm at 170k. I was thinking o2 sensor before doing a converter. Could that cause the jerking when coming to a stop?

I guess if your fuel mixture is getting way out of whack.

There are a number of things that could be causing that. Bad throttle position sensor, bad idle speed control motor, bad spark plugs. You know when the spark plugs have been changed? If you had a bad spark plug, you could have excessive HCs that an ECU can't correct which would throw your Cat code.

Not sure. But I thought about plugs too. I bought some yesterday. They're getting done this weekend, along with brakes.

Unrelated to this issue... since you are new to this car, what other things do you know have been changed? Timing belt?

timing belt, water pump, belts, valve cover gasket, and a bunch of other gaskets. Previous owner gave me all service receipts. Not with me currently.

Welcome to CL cptndan.

Are you getting a "rotten eggs" smell while driving? It's usually a sign of a catalytic that's acting up. Not necessarily a sign of a bad converter but one that is dealing with some sort of downstream issue.

I would look into the O2 sensor first because that's a cheap fix compared to the catalytic. I had that same exact code on my 2GS430.

I should have gone the O2 route first, but I did in fact go to two different places including the local Toyo stealership to confirm my problem and it was the right side converter. Previous owner merely cleared the code before he sold it.

Once that problem crops up the owner needs to fix it or risk a cat replacement. If it turns out that's the case, Magnaflow makes converters that will work, even a 50 state legal one. That's what I've had on mine for 2 years now. No problems.

No smell at all. And the o2 sensors are about $99 from local auto zone. The cat is roughly $110. So not much of a price difference. Unless the sensors are cheaper at Toyota/lexus. And did I read that we get a discount for being a member of this forum?

For a cat that is cheap like that, you will have to have it welded in likely. I live in CA so my options cost way more. I will likely just buy the whole unit when it goes out at a cost of between $500 and $700. When that happens, I will replace all the O2 sensors at the same time.

Rockauto has the O2 sensors cheaper.

We used to get a discount at Sewell Lexus but no longer. Too bad as I bought a lot of parts from them. If you look up the Toyota part number, check on eBay. I buy most of my parts there now.

Denso O2 sensors on Rockauto are ~$50 a piece.

Yeah, I've never used rock auto. But I just checked and they're like half the price. How do I know if it's cylinder 1-3 or 4-6? Or should I just do both downstream?

Yeah, look at the Rock Auto ones for O2 sensors - Denso is better. No smell? That could mean you just have a flange leak or some other issue that's not related to the cat all. You could replace the O2's and reset the code and see after that.

The cheaper Magnaflows won't necessarily clear emissions testing but the 50 state legal ones will.

cptndan,
Please, check this thread.
https://www.clublexus.com/forums/gs-...p-plzzzzz.html

But, first check for any exhaust leak, sensors and then the mid pipe or Y pipe. I do everything, change all the gasket, all 4 O2 oxygen sensor and at the end was the small cat. Is the last one on the exsahust that start clogger and that was the same code that show all the time on my obd ll. The small cat start clogger and everything start come back to the first O2 oxygen sensors that actually is the last 2 sensor and made the code show up all the time. Again check also that thread and the small cat. If is you have a 2jz engine. Good luck