thomas 777

jakemt

I will keep the post updated..but from what I am reading, 420 and 430 codes seem to be an "open your wallet and pay for whatever the mechanic says" code:-) What I think I have in common with you, is that I fully tuned the car and I used a valvoline or gunk injection cleaner to clean the TB. I sprayed the stuff with the car running (keeping the rpm's up so it did not shut down), thinking that would force all the crud through and out of the exhaust. If residue from that cleaning ruined the cat or 02 sensor, and if there is not a way to reverse/fix that as far as removing any residue that may have settled in the cat or o2 (assuming that theory may be correct), then I caused the problem and must bite the bullet.

There is nothing else I have done to justify this code and the car was running perfectly before I tuned it. I have checked for leaks, mistakes, I even pulled the new plugs and regapped them after reading that the gap should be .32 and not .44. I have retraced everything I had done.

At any rate..onward I go.

thomas 777

I wanted to wait a few days before responding. As you know, I tuned the car and the P0420 and P0430 errors appeared.

I tried everything suggested here, but read on a Toyota forum where a guy had a similar scenario. I retraced everything..no fix.

Finally, I pulled the plugs and got a set of NGK 3764 - Iridiums.

Reset the codes - light has not been OFF ever since !!!!

My first set were Platinums. I have no idea why, how or whatever, but it seems to have been the plugs. Car runs perfectly now like it did prior to the tune up. Runs smoother and more responsive. I have to take another long trip this week and if it stays off, then I will be convinced totally.

I am wothout words on this one. I had no idea plugs would cause this error, but go figure...the light is out :-)

Hope this is of help to others.

jakemt

Tom, just checking how you made out with those codes on your trip. Is the CEL still off? I read somewhere that if you have pre-detonation, no matter how minute, it might cause the unburned fuel to trigger those codes. You did say that the codes appeared while you were on long trips. Did this happen right after filling up at unfamiliar stations? With the cost of gas lately, I would not be suprised that some stations are passing off regular gas as premium. Its been known to happen. Since you installed new plugs as well, they can also be a contributing factor to engine knocking with bad gas. The old plugs might have been worn to such an extent that pre-detonation would be minimized even with bad gas. This is also possible with the iridium plugs since they have much smaller electrodes than regular plugs. A theory only. What do you think....?

Scooter99

iTrader: (1)

I have not been on in here for a while, and I never normally post. I am a Lexus tech and may be of help to you for this one. I didn't read all of the post by the way so you may have said something that I will suggest trying. We'll start off with, those cats have been known to go bad and are very sensitive to anything other than gasoline, you stated that you cleaned the carbon in the tb. That may have caused the material inside the cat to deteriorate or fail. But more so I see that with those codes (which are very common on that car with that milage), the exhaust flanges (connect cat's to mid-pipe)directley after the cat slightley deteriorate from minor rust,the exhaust keaks out causing a false wave pattern read by the rear o2 sensors making the ecu think that the cats are not functioning properly. If you can get under the car while someone gradually pulses the throttle you can feel with your hand if it is leaking. Visually you may be able to see black sute around the same area. That will indicate an exhaust leak. This should help

blkstealthpaid4

Hey Tom, I just bought my 1995 ls and I have had this code from the previous owner and it keeps coming back after I reset it.Did this code come back after you changed the plugs to iridium.What else did you guys do?

blkstealthpaid4

cement sealer on each precat joint or repolace gasket.

CMWis300

Po430 code fix. I battled this for a month and came up with a good cheap fix. I had the po430 code on a 2002 IS300. The cheap fix is to tie both of the bank 1 & 2 sensor 2 input wires at the ecu to the bank one sensor 2 output at the ecu. I used one gold plated butt splice connector at the ecu plug. You must leave both sensors and wiring in place good or bad for the heater load and bank one o2 sensor 2 must be good. You can find the pin out wiring diagram online at o2simulator.com. I feel as though it is a design flaw that everyone over 100K will have to deal with. You can spend thousands on cats and o2's and labor or a 20 cent butt splice connector. Hope this helps everyone.

striderg3

would this work on a 2006 GS430?
how much should replacing one of the O2 sensors cost if it really is my O2 sensor going bad in bank 2.
I have code P0430 also. bank 2
No smell from exhaust but check engine is on . accompanied by two other lights.
and I would say the power im getting from the car is not sufficient.