curiousB

Dash lit up last week with some warm weather. CEL went on, TRAC Off lit up, ! sign lit up, and the Check VSC was displayed in the info window.

Using OBD reader found error code P0104 in log. Seems to relate to MAF. Anyway its been a strange couple days of weather here (hot and humid) so wondering if its just a weather induced intermittent. I cleared the code and waited to see if it returned.

The next day I got another error this time it was P0430. Reset that code and filled up with fresh gas and did a lengthy 1 hour drive mostly at highway speeds.

Worked fine for a few days but it popped another code. I haven't been able to pull the code yet but wondering if this pattern is familiar to anyone. It sounds like I could fall into a bit of a black hole of parts changing.... O2, MAF, fuel cap o-ring, CAT gasket, and CAT. I'd like to target this a bit better b4 swapping expensive parts.

I guess I could do the easy stuff first, clean MAF with MAF solvent, check for intake leaks, replace fuel cap O-Ring. That seems a little hit or miss though.

Wondering if anyone else has had this error and if it points to bigger troubles down the road?


2004 LS430 105,000 miles, original owner.

StanVanDam

I haven't had this problem, but I recommend keeping track of all the codes, and then post them here if you need the troubleshooting steps for each.

P0430 indicates a problem with the Bank 2 Catalytic Converter. Is your handheld tool able to display the voltages of the O2 sensors? Have you checked for exhaust gas leakage? Are you able to measure the resistance of the O2 sensors? All 4 should measure 11-16 Ohms at 20 Celsius, and 23-32 Ohms at 800 Celsius.

If your handheld tester can do an Air/Fuel Control Active Test and can monitor O2S voltages, you can determine the cause of the P0430.

Worst case, you will have to replace your Bank 2 catalytic converter and front exhaust pipe.

Best way to avoid the black hole of parts changing is pulling all the diagnostic data you can, in order to identify the problem precisely. If you can hook your car up to a Lexus/Toyota Techstream system (all the dealers have this), then that would speed up the troubleshooting process.

curiousB

OK thanks. My latest code was a P0430 so thats a P0104, next day P0430, then 3 days later P0430.

So it is pointing more to the bank 2 area than the MAF now.

I did listen for a leak and didn't notice anything but I guess there could be a smaller one masked by the engine noise.

Might just take this to the dealer. I just don't want them throwing in an unneeded CAT, new pipe, new MAF, and a full suite of O2 sensors for good measure. Shotgun vs rifle.

curiousB

Car continues to pop P0430 codes the past few days. Maybe 4 times in last week.

Got car up on ramps and snooped around. Did notice a very slight leak at the flange after the CAT. Was slight but you could feel the warm leakage.

Went ahead and swapped the two downstream O2 sensors as they are identical part number. Will wait to see if the error code migrates with the sensor or stays on the right side.

If code stays on the right side I will then replace the flange gasket and see if that helps any. If code moves to the left I'll put in a new O2 sensor.

If none of this works its starting to pont to a new catalytic converter.. $$$ouch$$$

curiousB

Continue to pop P0430 codes. Did these logs of O2 data seems to suggest bank 2 catalytic ocnvert is gone bad.

Am I doomed to a new bank 2 catalytic converter? Any good sources at much cheaper than the $1100 Lexus list price for one?

CTGS

Just got the P0430 code today. Did you ever get the problem solved? Damn $1100? I just went to Autozone and they have one that is direct fit to the gs300 for $429 I wonder if its any good...

Lynzoid

hollow out your cats, replace innards with makeshift flame traps, then install these o2 simulators

they DO work on LS430.

curiousB

No still struggling with the problem. Mostly P0430 codes. I did try several things.


1) I replaced new gasket after the bank 2 CAT as there was a slight leak at the flange. Didn't fix it, still got P0430 code a few days later.

2) Bought a new CAT off of eBay for $180. Installed but came with very poor gaskets. Didn't solve problem. I am going to try to reinstall this weekend with Lexus gaskets but I don't think it will resolve issue. I think the OEM CATs may be California compliant so more effective than 48 state CATs which I bought.

3) I did put an O2 spacer to move secondary O2 sensor of direct exhaust path. That helped for a couple weeks but now I'm popping codes again. Maybe need a second unit to space it further but not anymore room as sensor almost touching side wall now.

4) I do have a slight leak at the flange still. Hopefully new gasket helps but old flange is a little corroded so not a clean surface for the gasket to mate to. Also some pinhole leaks in pipe after the secondary O2 sensor.

Lynzoid

No need to space it further... I have hollow cats and only about 1.5in spacer. I also have slight exhaust gasket leaks but these does NOT trip P0420/P0430.

At this point i'd recommend using any FAST OBD2 scanner, to see the graphs from the post-cat o2 sensors. It may be, that right sensor (p0430) is 'asleep' and 'wakes up' from time to time. It's a classic sign of o2 sensor failure.

edit: to elaborate further, p0420/0430 is tripped, when COMPARATIVE reading from pre- and post- cat o2's closely match for a predefined period of time (1min or so). That way ECM can tell, that there's not enough 'catalysation' left in cats.... But i also have seen it trip with faulty ('sleepy') o2 sensor (p0420 in my case as it was driver side one).

curiousB

Well I squeezed in a second anti fouler to space the O2 sensor further out of the exhaust stream plus it has just a 1/8" hole in the end (see thread below). The issue is these move the O2 so the wires are pressing against the aluminum heat shield. I was able to bend it a bit for clearance. The 90 degree version you mentioned would work much better. Since I had an extra anti fouler (sold in 2 per pack) I decided to try this.

Secondary O2 readings from OBDII showed an almost flat reading which is quite a bit different than just the one spacer (was moving around quite a bit). Just wondering if ECU will now pop another error saying O2 sensor inactive.. I guess we'll see after a few days.



http://forums.evolutionm.net/evo-how...ouler-how.html

http://www.b15u.com/sentra-specific-...or-spacer.html

Lynzoid

no, it won't.. it looks for flat line

curiousB

I'm not sure the algorithm to trip the P0430. It has something to do with comparing the waveforms between the primary CAT O2 sensor and the waveforms of the O2 sensor after the CAT (secondary O2 sensor). The theory is that if the CAT is functioning properly the frequently changing waveform in the primary O2 should be much different in the secondary O2 sensor. The secondary signal should be very damped and toggle back and forth much slower than the pre O2 sensor. In fact a sign of a poorly functioning CAT is that the waveforms look similar implying the CAT isn’t doing much of anything (acting just like a piece of pipe). In such a case an overactive signal on the secondary waveform trips the P0430 error code.

So adding extenders to the secondary sensor is in effect limiting its ability to track with the exhaust gasses. The name simulator is really a misnomer since it isn't simulating anything, it is buffering the sensor from the exhaust gasses.

The only question I don’t know is there a different P code for underactive secondary O2 sensor. In other words if the signal becomes too inactive does the ECU say, hey that’s not right either and trips a different P code. So far after two days I haven’t tripped such a code but I probably need a week or so of running around before we can conclude on this point.

Lynzoid

no there isn't more codes.... i drive like this for a year now and NO codes pop up ever...
and i had to improvise and make own curved extenders.
this is real money saver

curiousB

Well the plot thickens. I have been a little over a week and no P0430. I was starting to think the O2 sensor modification was going to stop the CEL and other dash light irritants. Yesterday I popped a P0156 which is bank 2 O2 sensor failure.

So the logic in the ECU to determine if the catalytic converter is working is a little more sophisticated than I had hoped. By adding the spacers to the O2 sensor it stopped the P0430. This occurred because the sensor was out of the mainflow of the exhaust gasses. As a result the signal from that sensor became very flat and didn’t bounce around like the O2 sensor before the CAT. Now we see it was too dampened and the ECU has flagged the sensor as non functional.

So it appears this sparkplug fouler modification for secondary O2 sensors won’t work for a Lexus. It’s too smart for this…. I found this report that seems to explain why it doesn’t work.

http://reviews.ebay.com/Truth-about-...00000002812356

One method is to measure the signal strength of the downstream sensor. As the oxygen content of the exhaust goes down, the voltage of the O2 sensor goes up. This voltage is generated by the sensor itself. So on a functioning converter, the downstream voltage should be at least a certain amount, typically 0.4 - 0.6 volts or higher. O2 simulators do not accurately replicate this voltage level. Another method is to measure response time. The response time method is based upon the oxygen storage capacity of a functioning converter. The vehicle will occasionally switch to a rich or lean phase for a slightly prolonged interval, and measure the amount of time it takes for the rear sensor to mirror the change. If the signal is consistently outside specifications, the computer will set a catalyst related code, and the CEL will illuminate. O2 simulators can sometimes produce a sufficient signal delay, but this is a matter of luck.

I also came across this article suggesting the secondary O2 sensor is used periodically to trim the primary O2 sensor as a health check. Its hard to see how this would work properly if you manipulate the secondary O2 sensor..

Note: Be cautious of O2 sims that replace the rear O2 sensor with a falsely gererated signal.

Toyota started using a wideband type O2 sensor (air/fuel ratio) in the front position for better engine control. These wideband type sensors need to be recalibrated from time to time by the ECU. The ECU uses the rear sensors for this recalibration process. The ECU cannot properly recalibrate the wideband sensor using a falsely generated signal. This process is explained here, US Patent 5706654.

http://www.google.com/patents?id=e1Q...54&output=text


I think most of these sensor spacers (so called simulators) are bogus.

I have noticed my leaky Y pipe after the converters seems to be getting louder so the leak(s) must be getting bigger. I plan to remove the O2 sensor spacers, reinstall the bank 2 OEM converter and remove the Y-pipe plus secondary converter and get the hole(s) welded with small patches. I’ll see if they can clean up the flanges with some welding/grinding as well.

With a sealed system if I pop another P0430 then I’ll admit defeat and head to the dealer.

Lynzoid

Well, you can think anything you like, BUT i (again and again) USE 2 spacers for 14months now, with completely emptied out cats, and i had NO errors for this whole duration WHATSOEVER.

Also, i have to note, that P0156 may just indicate faulty o2 sensor... Yes, i did replace one (bank 1 postcat) about 2 years ago due to it being sleepy...

I think i gave more than enough info in this thread.