OBD II Codes P0420/P0430, 2003 Highlander 2.4L

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Originally Posted By: DBMaster
Originally Posted By: The Critic
You should always check for any applicable TSBs before jumping to conclusions. There's an updated ECM calibration available to address the P0420 code on this car: http://www.toyotapart.com/ECM_CALIBRATION_UPDATE_M.I.L._ON_DTC_PO420_AND_OR_PO430_T-EG041-05.pdf However, at 150k, there's a good chance that it needs a CAT anyway, but the updated calibration is worth a shot and should still be loaded, IMO.
OK, I'll be a pain - just a bit. Two of you said I could not get a P0430 on this engine because it's a 4 and not a V6. That seemed logical to me, however, this TSB states that you CAN get both codes on the 4.
You can get ANY sort of code if the ECM gets confused. And that's exactly what's happening here. That TSB clearly states that it is OBSOLETE. This TSB has been replaced by Special Service Campaign 60I (apparently that's an "i", not a one). Basically, there is a problem with the ECM's firmware, and it needs to be updated to correct the problem. You need to visit your dealer, and have them look up Special Service Campaign 60I on TIS. Once the update has been performed, a sticker will be applied to the underside of the hood, which gives the details of the modifications.
 
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Originally Posted By: Vikas
Looking at the possible O2 sensor signal error codes, there is not one for "too much activity"! This implies "too much activity" is NOT one of the failure mode for an O2 sensor. This means if the rear O2 sensor is switching too fast, it is NOT because it is broken. Anybody recommending to replace rear O2 sensor when ECM detects too much activity is not dispensing the logical advice.
It is actually possible for an O2 sensor to be damaged in such a way as to present too much activity. Removal of the cover/shield/screen/cage (call it what you will) portion of the sensor would cause this type of failure. It would be a simple matter of unscrewing the sensor and looking at it to determine if this has occurred and there's no need for parts substitution as a diagnostic technique. It it looks broken it is. If it doesn't look obviously broken, nope, not broken in such a way as to show too much activity.
 
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Essentially, then the same principle used by anti-fouler is in effect, except in reverse! Instead of getting less flow, it is getting bombarded with more flow causing it to switch rapidly. Is that what you are saying? If so, I can't argue against it! I do wonder if I take a lazy sensor and enlarge the holes in screen/cage, could I reuse it again? If your argument holds, then it should be possible, right??
 

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I just got done taking the measurements. Whoever said this car does not have two banks is wrong. The cat has two O2 sensors at the top and two at the bottom for a total of FOUR. The part that the Toyota dealer replaced two years ago was "Bank 1, Sensor 2" part number 89465-48070 for $163.97 (part only). The cat is bolted directly to the exhaust manifold and it was hard to get a good pre- reading through a slit in the heat shield, but here's what I got. At Idle: pre-300, post-470 At 2,500 RPM: pre-270. post-400 It appears that the catalyst is still quite functional. Also, after a week the CEL has not come back on. I am thinking that some good gas for a while along with PEA cleaner will probably be a decent fix for the time being.
 

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In case you are wondering why there are two banks to this cat. The exhaust manifold and cat are actually a single assembly, too.
 
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Originally Posted By: DBMaster
At Idle: pre-300, post-470 At 2,500 RPM: pre-270. post-400
Those numbers look good. Plenty of action taking place in that cat. It would be hard to condemn that unit with these numbers. Keep an eye on it, the PEA cleaner may help.
 

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I am hoping so. The photo above was grabbed from Rock Auto. I know that aftermarket cats are not recommended, but regardless of the source these are expensive. The Walker brand cat pictured is about $450. The OEM cat is close to $700. And, from the picture I am sure you can see why.
 
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Originally Posted By: DBMaster
I just got done taking the measurements. Whoever said this car does not have two banks is wrong. The cat has two O2 sensors at the top and two at the bottom for a total of FOUR. The part that the Toyota dealer replaced two years ago was "Bank 1, Sensor 2" part number 89465-48070 for $163.97 (part only). The cat is bolted directly to the exhaust manifold and it was hard to get a good pre- reading through a slit in the heat shield, but here's what I got. At Idle: pre-300, post-470 At 2,500 RPM: pre-270. post-400 It appears that the catalyst is still quite functional. Also, after a week the CEL has not come back on. I am thinking that some good gas for a while along with PEA cleaner will probably be a decent fix for the time being.
Would never have thought Toyota would put a single cat on the manifold of a 2003 Camry with a 2AZ-FE I4, dual cats on the manifold of a 2003 Highlander with a 2AZ-FE I4. Same exact engine, same year, different manifold cats. Must be the exhaust design, no room underneath for a second cat or something. I have a non-fouler installed to extinguish the light. Its been on for thousands of miles. With the efficiency threshold set so high, my cat has plenty of life left on it even though the light went off a long time ago. P0420/P0430 is a efficiency warning, not necessarily an indication of failure. The CEL threshold may be much higher than what your state requires to pass.
 
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Leaky, thank you for reminding me about the non-fouler. I watched a video online about that. Did you drill yours out to 1/2" like in the one I watched? Both of the post sensors are fairly easily accessible. One of the nice things about this size engine for the Highlander is that there is lots of space in which to work. I changed the serpentine belt on this car in less than fifteen minutes a couple of years ago.
 
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I went smaller, 15/32. Kept rounding/enlarging until the sensor tip barely fit through. That allows me to use only one non-fouler rather than 2. Keeps exhaust flow at almost 0 and the sensor close to heat some need for status ready. 2 sticks out pretty far. Assume Dorman Help 42009 at AAP will fit with yours, but I also thought you had a 1 cat setup, so conform that. blush Has 2 in the pack. Drill 1, if needed the second caps it off.
 

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Thanks, guys! I see the Dorman parts on the O'Reilly's web site (No AAP's around here) and I see the extensions on eBay. If her CEL codes again I'll go that route. Is that not an outrageous cat setup?
 
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Originally Posted By: Vikas
4) Google O2 sensor extension (If anybody asks, you did NOT get it from me!)
I'd be a little careful with this. They know about it and do look for it in NJ at least. I beat it only once and that was after painting the anti-foulers with Bronze-Tone to match exhaust and not be all shiny new and stick out to the under car cameras. But I do get a P0000 code which I fail for just because the light is on. Shut with Scanguage, and it comes right on, and you fail for just the light in NJ, no matter the code is an "error, there is no error" code. I beat it now with O2 simulators now. I know two people who blame me to this day for their cars seizing up because of this. They insist it was from a leaner fuel mix, which is already VERY lean in a lot of vehicles.
 

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She got this vehicle about four or five years ago with close to 100,000 miles on it. It was a real cream puff, though, and super clean. The guy who found it for her was one of those "boutique" used car guys who was a friend of the family. So, it very well could be from California. If shielding the post sensors leans out the mixture I am not sure I'd want to do that. But, given the junk gas she has been using a good cleaning may help. Plus, I am planning to change oils at the next OC and probably start using Rotella T6 5W-40. That cut the oil seepage past the valve guides on my old Accord and it ought to help out on this car as well. Anything that cuts down oil in the exhaust is bound to help as well.
 
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The pre cat o2 sensor performs the a/f mix function. The post cat o2 sensor's only role is to check efficiency vs. pre cat o2 sensor based on the warning threshold Toyota sets, not the feds or the state thresholds for emissions. Your just extinguishing Toyotas warning light. Fixing a CEL. Your not changing the emission results, smog test results are the same. So its fine. With one short 42009 on its hard to tell once it changes to the same color as everything else. You can always slap some grease on it, let it get dirty. grin
 
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Originally Posted By: OilFool
i do see their logic with O2 sensors possibility of being coated with oil/carbon and possibly leaning it out then reading even less with the anti-foulers installed
Back in the day of single O2 sensors that was possible but today its highly unlikely. Modern systems use an A/F monitor to handle mixture, the rear one jut monitors the cat. There are circumstances where it can effect the mixture like and exhaust leak in between the 2 sensors in the cat body for example but otherwise its not going to do anything. The guys on that forum as messing with A/F monitor settings with tuners and stuff so its no wonder they run into problems sometimes.
 
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