thomas 777

Hi all - I have a 97 LS400 Coach with about 195K milles. It runs absolutely perfectly. Here is my stickler:

I tuned it up in preparation for a 500 mile trip. I also wanted to replace the small hose the passes coolant through/around the throttle body... it was leaking a little.

When I loosened the TB ( I did not completely remove it), I saw a lot of carbon build up, so I used a spray to break it up... I replaced the hose, plugs, filters, wires and buttoned it back up. I did not disassemble it...just sprayed the opening that connects to the intake.

The Check Engine light came on. I left a connector loose at the MAF, connected it, started the engine again and it went off. So I assumed this was the problem for the CEL.

Driving back from the trip, the light came on again. When I got home, I ran the codes and got PO420 and PO430 error codes. Kinda vague in my estimation.

I really do not think it is an 02 Sensor or the (UGGH) Cat Converter, and want to get your best idea of how to trace the root of these errors and where to start. I only have the machine to retrieve the codes, a LOT of tools, and I am fairly good at mechanics.

Any help would be appreciated.

Thanks,
Thomas

jakemt

I came up with the same codes on my '00 ls400 although I did not do anything with the throttle body. When I recently had the 90k service done on my car, the Lexus tech said the codes have something to do with the tb and suggested i have it replaced. I said to him to just clean it so it may be somehow related. Anyone here have suggestions? Thanx.

GRAND_LS 4

iTrader: (2)

P0430 OBD-II Trouble Code
http://www.obd-codes.com/trouble_cod...old-bank-2.php

P0420 OBD-II Trouble Code
http://www.obd-codes.com/trouble_cod...old-bank-1.php

thomas 777

The explanations are much more specific than the readout on the reader I got from AutoZone.

I really appreciate the reply and will follow the steps as outlined on the links.

jakemt

Thanxs from me too, grandls. When i did the 90k service on my '00 ls a couple of weeks ago, the Lexus tech said that a catalytic converter gasket had to be replaced as well. I assumed he was correct since the car made such a racket once it was started. However, he also said that he was getting a code indicating that the tb was not functioning correctly. He suggested I have it replaced. Since I have some idea how these things work, I told him to just clean the sensor and the tb. Apparently, it worked for awhile but i'm now getting the check engine light with p0420 & p0430. I'm wondering if its somehow related to what the tech did since that catalytic converter gasket is in the same proximity as where those obd codes are indicated. In any event, the only driveability issue i now have is that there is some hesitation and vibration when the car is started cold first thing in the morning. Once it gets warmed up, there is no vibration and it drives very smooth. Let me know how you make out, thomas. . .

JLAM

iTrader: (1)

I get the same CEL code on my GS400. The car still drives normal. I usually just reset but it comes back on. Thanks for the tips and the link...I'll try it out and see what happens.

GRAND_LS 4

iTrader: (2)

Your welcome guys

thomas 777

I am tearing down the TB, got a new gasket for it, some new vacumm hoses and will retrace all I have done.

If the light still comes on, I am gonna buy this MIL Eliminator off eBay - unless you guys think it is something I should not do.

http://cgi.ebay.com/ebaymotors/ws/eB...0503401&rd=1,1

I just don't see or understand why this light would come on after over 190K miles of perfect performance and maintenance better than factory specs...

but then again, maybe it was all a coincidence and the tune up triggered something else. I just can't see taking it to a dealer and paying hundreds of dollars for something that may be a 2 dollar fix :-)

thomas 777

There a a bunch of these things on eBay or Google and they specifically mention the 420 and 430 codes and say it does not harm other error code readings.

http://motors.search.ebay.com/?from=...mil+eliminator

http://www.google.com/search?hl=en&q...mil+eliminator

I am not getting any foul smells that may indicate the Cat Converter and other than a vacumm leak or the temperature sensor, I am stumped..but I won't give up yet :-)

PureDrifter

iTrader: (10)

those, simply put, are evil.

they cause ur motor to run rich and are a mickey mouse way to fix the car. you WILL regret using them.

thomas 777

PureDrifter:

I think evil is a little much :-) I can understand the car running rich and I am not an expert at the device, and I appreciate your input. Do you have any facts to back up what you said?

As far as mickey mouse...maybe...but I am not gonna play bozo the clown at a stealership when all they do - at least where I come from - is load you up with parts that you don't need..THAT much, I am sure of. The links that GRAND_LS 4 posted were far and away the best path for me to take and after I am done retracng my work, the problem may be solved.

But anyways, I appreciate your input... I do not have a clue as to what those things do or don't do...that is why I posted the comments here. I figured maybe the experts could shed a bit of light.

All The Best

thomas 777

The Saga continues - I went back to the links you posted and read some related links regarding the P0420 and P0430 codes - and on one of the forums, a guy suggested cleaning the EGR Valve. So I said what the heck, I'll try that.

I cleaned the EGR valve, which was so full of crud, I used 2 cans of cleaner from AutoZone (the Shop size). I also used a can of electrical parts cleaner to flood the MAF sensor, and after retracing the previous work (didn't see anything amiss so far) I reset the code.

The bad part is that after driving for about 30 miles, I stopped and turned the car off...the light came back on after I started it and drive about 10 miles. But, initially it showed 4 errors - 2 420's and s 430's. NOW, it is down to 3 errors. 2 420's and 1 430. So it's 1 down, three to go.

Anyway, I am determined to get to the root of these errors, but I wanted to thank you again for those links. I'll keep plugging away until they are all gone.

It looks like hit and miss, but it's getting better.

justfixit

These codes are for catalytic converter thresholds being insufficient. They have nothing to do with EGR or throttle body. What these codes are designed for is to check the efficiency of the converter itself. How it checks is by comparing your pre-cat O2 sensor with the post-cat O2 sensor. If both sensors continually read the same voltage then the ECM assumes the converter is not operating. Most common causes for these codes are defective cats or exhaust leaks at cats. New gaskets is the cheapest repair attempt obviously.
P0420 is for bank #1 (driver side)
P0430 is forbank #2 (passenger side)
Good luck

thomas 777

Thanks and I agree with you about the code definitions...it was just weird how one of the error codes have now been eliminated after I did the additional work (which should not have effected it I guess).... going to check for exhaust leaks today.

Thanks to all for your input. I am just a die hard DIY'er if I can.

jakemt

I'm beginning to think my codes might have something to do with a recent service at a local lexus shop. About 3 weeks ago, I had the 90k done with the tech saying i needed to replace a catalytic converter gasket. He also mentioned replacing the throttle body. I changed the gasket but refused the tb and just told him to clean it as best as he can. Since thomas says that he got his codes after cleaning the tb, its possible some of that gunk might've gotten into the engine and exhaust system maybe causing some blockage in the system and/or coating some sensors.

Tom, keep us posted since I might need your findings to use as evidence when I go back to lexus service. Thanx.