A Few DTCs That Need Fixing...

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899
Location
Brooklyn, NY
My check engine light has been on for awhile with just P0446. I just checked it today to clear it, as I don't want the light to burn out (and have to pull out the instrument cluster to replace it!) and I found a few more random codes. The codes are: P0446, P1300, P0420. From what I read, the first one is related to the evap system, the second is the igniter circuit, and the last is related to catalyst efficiency. Any info you guys can give me with regards to tracking down the reason for P1300 and P0420 would be greatly appreciated! Car is a 1997 Toyota Avalon 1MZ-FE
 
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Messages
4,998
Location
Milwaukee, WI
The 420 is kinda a catch-all code that is usually the MAF dirty or the upstream 02 sensor giving bad readings, but it could also be the downstream or just a poorly running engine. I would fix the other two and see if that clears up as a result. the P0446 could be the gas cap, could be you need a new charcoal canister. The 1300, I don't have anything for you, sorry.
 
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11,658
Location
NorthEast
When you get *only* P0420, it indicates worn out catalytic converter. This is one of the most common CEL code on OBD-II cars. Do NOT try to change rear O2 sensor. If that was broken, you will get different code. If you buy aftermarket converter, the code will come back within few months. Only OEM converter will keep the code away for next 70~80K miles. You have to look at the Mode 6 test results to really find out if the computer is on the verge of giving you P0420. You can also look at the live data either via scanner or via dual-channel oscilloscope to compare front vs rear oxygen sensor. You want front switching very rapidly and rear switching very slowly. Computer counts the switching thresholds for both and when the ratio drops predetermined point, it will turn on the P0420 code. If you need to know more, google "Mode 6 P0420". You can always try snake oil remedies and keep the light away enough for emission test to pass; provided you complete the OBD-II drive cycle (look it up) before it lights up again. But in the end only brand new OEM converter will keep P0420 away for few years. I have been haunted by P0420 and P0430 on all my 3 vehicles for many years. And hence I have read on these extensively. For the evaporator code, first try to either replace the gas cap with OEM one or slightly oil the o-ring in your old gas cap. Also NEVER overfill your tank. Stop at FIRST click at the pump. Overfilling eventually destroys the canister. Assuming P1300 is the ignition miss-fire code on Toyota, I would start with the spark plugs and/or coil. I presume you have Coil-On-Plugs. Unless you have lots of money to replace all the 6 coils, I will wait until computer gives you cylinder specific miss-fire code. Ya, and buy a decent scanner so that you can monitor the codes and look at some of the engine parameters and/or freeze frame data etc. - Vikas
 
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parimento1

Thread starter
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899
Location
Brooklyn, NY
I figure I will go to my mechanic, I wouldn't even know where to begin with one of those scanners, and they are very very expensive. I do not, however, want to go to the dealer. I'd rather go to the proctologist than that : ). Thanks for the info though, especially on 0420. I am surprised that the cat will ever get fouled. I mean my car burns oil, but nothing that seems excessive.
 
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11,658
Location
NorthEast
One of the great scanner will set you back $150 and a basic code reader (comparable to what you borrow from Autozone etc) will run you $40. Both are shipped price to your door. It is up to you to decide if you consider them "very very expensive" None of my car burns any oil but I have P0420 on all my cars after ~100K on them. The computer wants over 90% efficient converter but they slowly starts dropping under that. Even with P0420, you will have stellar emission results, less than 1/10 of the federal limit, AS LONG AS there are no other mechanical problems with the engine. Mechanic will give you similar advice that you get here except you will be paying for it :-) Worse, he will start replacing parts at your expense without finding the root cause. - Vikas
 
Messages
39,806
Location
Pottstown, PA
 Quote:
Assuming P1300 is the ignition miss-fire code on Toyota, I would start with the spark plugs and/or coil. I presume you have Coil-On-Plugs. Unless you have lots of money to replace all the 6 coils, I will wait until computer gives you cylinder specific miss-fire code.
You are correct ..although I don't like the nomenclature. http://alflash.com.ua/P1300.htm
 
Messages
11,658
Location
NorthEast
As far as the overlap of your codes, I suspect not. OEM gas cap should be pretty cheap. First try that and see if evaporative code goes away. You might get lucky and after resetting the CEL, you might get only P0420 code back after few miles. If the wiring does not look like chewed up by mice, you have to eliminate bad plugs or bad coils as the source. Sometimes, the miss-fire code is triggered because your mixture is too lean. But generally, that results in P0171 and/or P0174 codes. On the off chance that the mixture is occasionally lean but not enough to throw lean code, clean your MAF using *only* approved MAF cleaner. CRC makes one in a red can. MAF's are delicate so handle it with care. If your MAF is dirty, this fix alone would make you amazed with the performance improvement. If you still get the P1300, then you might have to look at the state of the spark plugs. If you are running anything BUT NGK, get the OEM NGK in there. If you have Bosch, then this will explain P1300. The dual laser platinum NGK (about $10~$12 each!!) lasts easily in excess of 100K miles. I have yet to hear about a dual laser platinum NGK which came off a car after 100K looking worn out i.e. they all looked as if they would go another 100K. If you are not the original owner, it is highly likely that somebody replaced those expensive plugs with a cheapo versions and you are getting P1300 code. In that case you will end up spending $60 on the plugs and wait to see if P1300 returns. Once you are on the solitary P0420 (and/or P0430 I don't know if your engine has total of 3 or 4 O2 sensors) you start doing voodoo incantations to get rid of those codes :-) This is what a *good* mechanic will do. - Vikas P.S. And for God's sake, don't just disappear when this saga is over. 90% of these topics end up with NO resolution. The original poster never comes back to update the final outcome :-(
 
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parimento1

Thread starter
Messages
899
Location
Brooklyn, NY
Hi, thanks for your help, I will def post and tell you the resolution! I have had P1300 appear before actually, and it was apparently caused by a bad alternator, because it went away after my alternator died and was replaced- about 2 years ago. I just replaced the alternator again once the [censored] rebuilt one died, and started getting the code again. I wonder why that is happening. I replaced the alternator with one that puts out 100 Amps (it is one from the Toyota Highlander, as the Avalon one only puts out 80, and I have a small sound system in it ~350 Watts). Could this be the cause of P1300?? If you guys do not think this has anything to do with it, do you think it could be the crank position sensor in addition? The P1300 code for a TOYOTA is "igniter circuit malfunction" not "random misfire." Also, just to add, I pulled 2 spark plugs, one from each bank, and they both looked brand new. They were replaced at 60K miles (car has 153k now) with OEM NGK ones from the Toy dealer.
 
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Messages
39,806
Location
Pottstown, PA
Easy. Reset the PCM and don't use your sound system for a week. If no CEL/MIL occurs, return to using it and see if the code reappears. I guess a sag in current from a peak/spike could be read that way
 

parimento1

Thread starter
Messages
899
Location
Brooklyn, NY
ahhh thats a good point! I will also make sure the radio is off when the car starts, less draw is good, which is the only time the CEL lights up for that code- at initial start-up. A tell-tale sign that the car is about to throw that code is that it will crank for a split second longer than usual when starting, then the light will come on immediately. Then the car will be off and you go to restart it, and the light is off, (it goes off on its own). It has always been an intermittent problem, when present.
 
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