Cel - p0420

CitadelBlue said:
Seems I received several solutions including replacing the front and rear sensors (about $100 each) and or CAT ($300-?) ... ...but the REAL solution was to remove the gas cap .. then tighten down until I heard a few clicks, disconnect the negative side of the battery to reset the computer ...... and all is well......
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Probably not. The Cat efficiency test will probably show incomplete if you attach a code reader. It will usually take about half a tank's worth of driving before the test is complete after a reset and the code can be reset. If the sensor is marginal, it could be a few months before you see P0420 again. The gas cap is related to a few EVAP codes, but I doubt it provoked your p0420. Sorry to rain on your parade.
 
No parade today .. but it did rain allot down here in northern VA ... Just thought it odd yesterday when I first got the CEL. The weather had been cold, then warm but foggy, and I had just added about 6 gallon of gas to top off the tank (and was distracted when I put on the gas cap) and then driven about 3 miles. I'll keep this post alive when/should the CEL return .....
 
Things have been pretty busy for me as of late, so I haven't been on much at all the last few weeks. I've just been clearing the code when it pops up and plan to replace both sensors this spring when more paying work comes in.

As for my gas cap, I'm a habitual tighten 'til she clicks kind of person, then give another few clicks again. Just to be sure.
 
Its been a week. 8 gals or so of gas. And all seems well. I usually am pretty good about the gas cap as well, but just got distracted. AND ... the weather had just warmed up to a warm 60+ degrees, fog and all. I'm thinking maybe a bit of moisture in the fuel system as well.....l ....
 
CitadelBlue said:
I'm in northern VA , I have automatic and no CA emissions. Just looked under the 4Runner. Seems I have 2 sensors. One before the CAT with 2 bolts that hold it in place and one after the CAT that screws in like a spark plug. Is there another somewhere? Can I assume the front one is the Air/Fuel Sensor Denso part number 234-9002 and the rear is the O2 Sensor Denso 234-4622? and I need the rear one?
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what company were you in at el cid
 
Sorry I know this thread is a little old but I didnt feel like creating a brand new one. I had a P0420 code and I ended up getting rid of it by cleaning the MAF and resetting the code. I got the code right after getting gas at the sketchiest gas station in washington so that may have been the problem and simply resetting it was enough.

Before I got rid of the code I did go ahead and order a new o2 sensor thinking that was the issue anyways. It's been about 2k miles and now I have a sensor sitting around in its box. Should I bother putting this in anyways? Right now I get about 17 mpg hwy which is slightly lower than I have gotten before. The other option would be to ebay the denso sensor and take a slight loss on it, or possibly just hang on to it?
 
Action.Jackson said:
Sorry I know this thread is a little old but I didnt feel like creating a brand new one. I had a P0420 code and I ended up getting rid of it by cleaning the MAF and resetting the code. I got the code right after getting gas at the sketchiest gas station in washington so that may have been the problem and simply resetting it was enough.

Before I got rid of the code I did go ahead and order a new o2 sensor thinking that was the issue anyways. It's been about 2k miles and now I have a sensor sitting around in its box. Should I bother putting this in anyways? Right now I get about 17 mpg hwy which is slightly lower than I have gotten before. The other option would be to ebay the denso sensor and take a slight loss on it, or possibly just hang on to it?
Click to expand...

i just threw this too. i may try to clean my MAF later today aft work.
 
CEL P0420 has to do with the O2 sensor and CAT. All I did was reset the CEL (Disconnected the battery) and tightened the gas cap. I figured the weather had just warmed up adn I just got gas and probably a little moisture in the gas. The light stayed off. However, after maybe 2000 miles of which 1000 was interstate driving and after a fill up the light came on again. This time P0171.... I hanged the gas filter (never had done this, cleaned the MAF with the store bought cleaner, change the O2 sensor (the one AFTER the CAT) and the light kept coming back on). I finally changed the MAF and put on a new air filter. The light has remained OFF for at least 800 miles .... See this thread too ..... some good info here .. http://www.toyota-4runner.org/3rd-gen-t4rs/85363-p0171.html
 
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