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P0420 running out of repairs

24K views 35 replies 15 participants last post by  meyameanne 
#1 ·
Hopefully you all can double check my madness and lack of dealer support

2002 Toyota Camry
2AF-FE motor 2.4L
5 speed manual trans
approx 167500 miles
oil change / filter change every 3000 miles

The P0420 code tripped off about 2 months ago. It reads Catalyst System Efficiency Below Threshold (Bank 1)

The local Toyota dealer sates the first catalytic converter to be changed out.
About a week later the same code goes off. Back to the dealer. This trip the dealer changes the Variable Valve Timing. Then after a few hundred mile trip the code comes back. This is the point I found the nation. Searching here I have replaced the Mass air flow sensor and the bank 1 O2 sensor. Code was clear for about a week. I did the O2 spacer on bank 2. This lasted over 2 weeks with almost all freeway miles. I also used B12 chemtrol at this time.
Now after a long freeway trip and some town mileage the code is back.

The car is getting normal gas millage. Drives every day. Id say 40% is freeway miles.

I thought about changing the fuel filter and screen. Toyota states the filter is lifetime unlimited mileage. The spark plugs have been changed month prior to the code showing up.
The coil packs are factory and I have had no codes for them

This weekend I'm going to clean the throttle body. I doubt it is the issue.

I have read where the ECU may need to be flashed. My local dealer has not looked into that.

Is there any other things I can do before going back to the dealer?
 
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#3 ·
P0420 according to the documents I see are Converter, front pipe, exhaust leak, or one or both sensors. Now it could be one or multiple items. I also see a TSB where the converter needs to be replaced and the computer reflashed, but the computer reflash only needs to be done once, so it may have already been done. That would be for the dealer to check.

I asked a tech and he and I can't think of any reason why the variable valve timing would be replaced for a p0420 code. I hate to second guess another dealer because I am not seeing what they are.

I hope this information serves you to assist you in getting this resolved.
 
#4 ·
I too thought the timing was a wild idea. Called the dealer and they suggest injectors to be cleaned. Ill have them do that Ill ask them to check and see if its been flashed.

One of the last things I did is the anti fouler.

Ill keep you posted
thanks guys
 
#5 ·
How many catalytic converters does your car have? A P0420 is for your O2 sensor, which is the sensor after the cat/s, the sensor in front of the cat/s immediatly after the exhaust manifold is an AFR sensor...narrow band, but still for AFR not O2. If there are more than one cat then it may be the second cat. I'll also go with it could be an exhaust leak too, but it would have to be a pretty bad one. Check all the mating joints for exhaust while the vehicle is running, it may be worth it to just change the gaskets anyway. And FWIW, a P0420 code will not effect the way the engine runs AT ALL, your O2 sensor is purely for monitoring the catalytic efficiency of your catalytic converters, NOTHING ELSE. I also recommend the non-fouler setup if your O2 sensor is the screw in type, which, knowing Toyota, its probably the two bolt type. Basically all you need to do (what the non fouler does) is get the O2 out of the direct exhaust stream so it will sniff less exhaust gases and not see the cats not doing their job.

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#6 ·
And also FWIW, of you are paying for all this maintenance then that variable valve timing job they did was bogus as hell, they got you good on that one...if it was some kind of warranty work or something, then let em change everything until the car is new again, haha

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#8 ·
Reflash for sure.

Was the converter replaced with an OEM converter? Did anyone check the wiring harness connections at the 02 Sensor and ECU?

It sounds like your dealer is full of parts replacers and not technicians. I have never seen anything with VVT-i cause a P0420 (computer thinks Cat is not working properly based on readings from the rear 02 sensor).

I would find another dealer.
 
#13 ·
The non fouler is installed just like the posted pic.
the bank 1 sensor is still attached to the header like it came from Toyota
I have looked a the wires and connections on both O2 sensors
I have not yet pulled the glove box to look at the ECU harness

The dealer checked the fuel pressure and throttle body. All were within specs.
They could not see why the code is showing up.

Once we mentioned the TSB they said they were aware of it. They did not flash it at this time.
They have to check with some higher up but it sounds like they will do the flash for free, do to the fact they charged us for the VVT that as many above stated was a waste.

Today I pulled in my OBII scanner ( innova 3120) to check for pending codes. No dash light today. The dealer must has cleared out the codes. As there was no pending codes. But it is not running like it use to.

I also notice that my scanner could not pull the cars VIN.
To test my scanner I went to my dads 2001 F150. It pulled the VIN.

Could this be a sign of the ECU failing?

Now the car is lagging during acceleration. Acts like a clogged fuel filter. Toyota says the filter never needs to be changed. Hence looking for pending codes. Im thinking the dealer did something during the fuel injection cleaner.
 
#14 · (Edited)
Toyota didnt start actually programming VINS into ECUs until around 2006 (although the option exists). No surprise yours isn't programmed.

VVT-I was a replacement for vacuum advance distributors in that a car needs good emissions at certain ranges and good power at certain ranges. Advancing timing is the easiest way to do that. My 82 Corolla accomplished this by using vacuum to advance or retard the distributor timing base on engine load.

Have them do the reflash since it seems they are doing it for free. Then if no dice the actual connectors need to be checked for resistance and voltage to make sure the wiring is in working order sending and receiving the proper signals. If for example the wiring to the 02 has a high resistance then the computer may see this resistance as a high reading and confuse it as a problem). If everything checks out there then the ECU may simply have failed.

The problem is that the dealer has an entire flow chart diagnostic telling you exactly what to check at which step. Parts replacers never read this and just guess and guess. But real technicians read these areas and diagnose accordingly.

As for idle check the throttle body to make sure it's clean. If they unplugged the battery and the throttle body was dirty your idle will be affected.
 
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#16 · (Edited)
Tell the dealer to stop throwing parts at it and follow the dtc trouble code diagnostic tree instead of wasting your money. Hook a code scanner up to it that shows live and freeze frame data. Verify that both o2 sensors are switching back and forth and that one isn't stuck in lean or rich. Your car should have 2 cats. But no o2 after the second one.
 
#18 ·
I had the same code on my 03 I4 Camry for almost a year. From all the research I did online, it looked like it was most likely the catalytic converter. Every time I used the diag tool to reset the light, it stayed off for 100-150 miles then came back.
This was way too costly of a job for me seeing as how it didn't severely impact the way t he car operated and would cost at least $600 to get done (including the ECU reflash).
About a month ago though, the car became very loud and when I first turned it on everyday I could smell exhaust fumes. I took it to a trustworthy muffler shop and he told me the flex pipe was no good. He did the fix for $120 and I reset the light. This was about 6 weeks and 1000 miles ago, the light is still not on.
Hope this helps.
 
#20 ·
Don't quote me but,

O2 sensors produce their own voltage in a analog sort of way(acts as a galvanic battery). As the voltage rises and falls they produce a crosscount at the 0 mark. It's these crosscounts that are monitored for correct operation of sensor under certain parameters.

Sometimes the sensor will skew to a richer or lean reading even though it's not the case in the exaust stream. O2 sensors only measure oxygen(lean) or lack of oxygen(rich). If you have an exhaust leak anywhere upstream from the sensors it must be repaired for proper operation.

It may be your upstream skewing and causing your downstream to react.

I believe the only practical test to call which cat is going bad is to temperature probe(lazer temperaure gun) the inlet as compared to the outlet which should be hotter than the inlet.

Apologies, not written very clearly, hoping it helps.

Cheers

P.S. If you install the sensor yourself be sure not to touch the tip and if using anti-seize compund it must be O2 sensor safe.
 
#21 ·
I am not an expert but at this point these are the things I would look at:

1. Is B12 Chemtrol sensor safe?
2. Did anti-sieze or any chemicals get on the o2 sensor during reinstall?
2. Are you burning any oil? The cat should last the life of the car unless your car is running inefficiently or you are burning oil.
3. Did you do the spark plug fouler trick before the code came back in? If so, do you live in a cold climate? If the downstream o2 sensor doesn't reach a certain temp in a certain time frame then it will throw the code. The fouler pulls the o2 sensor out of the exhaust path a little and if ambient temp is low then it may not warm up fast enough.
4. I would suspect a defective downstram 02 sensor at this point and I would try replacing it again.
5. ECU would be my last guess.
 
#23 ·
This is a really good link for understanding and testing converters:
http://www.aa1car.com/library/converter.htm

Too bad you got the 3120 innova. For a little more you could have got one with live data that would help with this diagnosis.

Seems like the dealer should have done some easy tests on the cat and exhaust to see if the problem is sensory or actual.

I saw a post on the Corolla forum where long term fuel trim defaulted to 18 after clearing the ECM
http://www.toyotanation.com/forum/131-8th-generation-1998-2002/417407-p0171-p0420-ive-tried-everything-2.html#post3932841
 
#26 ·
I checked amazon to see if the 3120 has live data and I saw in one of the reviews that the 3120 doesn't, but a similarly priced 3130 does. Maybe there are other tradeoffs - I didn't look closely.
http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=innova+3120


I know the Actron 9580 has live data - that's the one they let you borrow at Advance Auto. If you own a laptop you can get a lot of functionality cheap by getting the Elmscan tool.
http://www.auto-facts.org/automotivescantoolreviews.html#.UDVfHE1lSkX
 
#27 ·
Thanks for all the replys
My dad got it to the dealer and they checked the ECU and it is fine.
The lag during acceleration is now worse. The dealer could not figure that out either.
I used the antisense that came with the sensor. I made sure it was only on the threads.
B12 is sensor safe. Its a deson sensor. That supposedly what is OEM. The dealer said the sensors are fine.
The next step is to call Toyota District office. Hopefully they will bring in a master technician.
 
#28 ·
That really really sounds like a plugged up cat. Really odd though


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#29 ·
AS Black Cam Se said you need to have a tech follow the diagnostic tree and not throw any more parts at the car until you get a good diagnosis. If you want to do the diagnosis yourself, I understand that Advance Auto has the code reader with the appropriate diagnostic logic for each code at about $100. ONe has to go through each step in order and not skip around to determine the problem. Do you know the O2 readings? If the car is running lean you probably have a leak in the egr or intake system?
 
#31 ·
If you want to do the diagnosis yourself, I understand that Advance Auto has the code reader with the appropriate diagnostic logic for each code at about $100.
For that kind of money I think you'd be doing better getting the factory service manual, which has the diagnostic flow charts + much more. Even so, you really have to understand the systems because the flow charts are not always complete and infallible. As much as they purport to be. I think the later the year, the better they get.
http://www.ebay.com/itm/OFFICIAL-FACTORY-TOYOTA-service-shop-mechanics-REPAIR-manual-CAMRY-2002-set-7-/120945295443?pt=Motors_Manuals_Literature&hash=item1c28e6c053&vxp=mtr#ht_1512wt_1244
http://www.ebay.com/itm/2002-Toyota-CAMRY-Service-Shop-Repair-Manual-Set-FACTORY-DEALERSHIP-OEM-HUGE-/160870717338?pt=Motors_Manuals_Literature&hash=item2574a4579a&vxp=mtr#ht_521wt_958

The manuals are good to have even if you don't do it yourself -- just to elevate your game, in general.
 
#32 ·
It goes back to the dealer on Wednesday. The local dealer master tech is off for two weeks. The district is having his assistant try to fix it. Toyota district office said that if this tech cant fix it they will send in a master tech. I assume from another dealership.
 
#33 ·
Hi Busted Toy,
I was looking thru my papers and happened on the Technical Service bulletin EGO24-04 3 April 2007 for MIL 420 affecting the 4 Cyl 2AZ-FE. The fixes mentioned are to flash the PCM and if this does not work to change out the Catalytic Converter and under warranty if the car has less than 80K or younger than 96 months.
I can fax the TSB to you if you want.
 
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