Need A Little Help! (1 Viewer)

Joined
Feb 23, 2014
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32
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Phoenix, Arizona
Hey guys, I'm currently overseas in Iraq at the moment. I've been having my fiance drive my 80 around the neighborhood while I'm gone. The other day she went to fill up the tank and while driving that evening the 'Check Engine' light came on. I told her to take it and get the code ran and she went to Autozone and it came up P0420, and the guy said he couldn't reset it.

I just went thru emissions a few months ago with no problems. Can anyone recommend my next course of action for my fiance to take? I won't be back for a couple months and I don't want this to turn into a more serious problem.

Cheers in advance.
 

Funner

SILVER Star
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Jun 29, 2011
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3,218
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Phoenix, AZ
Just make sure it is P0420 (Catalytic deficiency) and not P0402 (EGR). I had someone read the nuber incorrectly to me and ended up chasing a phantom until I retested it and got the correct codes.
P0420 can be caused by bad O2 sensors, bad cats, exhaust leak, egr leak and even higher butane levels in gas blends. I would discount the higher butane levels as winter blends are not supposed to be available until Sept 15th.
If your cats were replaced with aftermarket even a couple years ago that could be the issue.
If it's running fine I wouldn't worry about it until you return.
 
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murf

Lifer
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Jun 24, 2007
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Scottsdale, Arizona
Funner is right - It will not turn into a more serious problem. It sounds like its not her daily driver, deal with it when you get back if you want.

She should still drive it around the block every week with absolutely no worries about it.

x2 on the aftermarket cats
 

inkpot

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Jan 30, 2003
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All over Arizona
Been battling the 420 code on my rig for a while. It is my daily driver, and at first it would show up every 2-3 tanks of gas. But it gradually got more frequent. It did NOT affect the performance/drivability of the rig. So I went thru all the testing and I even replaced the ox sensors, but it did not make any change. Connectors and wires were all good, so I had my cat replaced, along with some other exhaust work. Not codes now. It has been several weeks of driving around the Valley, plus 9 days in Ouray of high altitude wheeling, and NO CODES!! I'm very happy.

The 420 code just means that the ECU thinks the rear ox sensor is reading outside of the rather narrow temperature range that Toyota programed into the system. It is only a measure of the cats performance/efficiency. The ECU does not make any changes in engine operation as a result of this code popping up. It will run just fine. John
 
Joined
Feb 28, 2012
Messages
933
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N. Phx
"fill up the gas tank, and later that evening (code)" = P0402, and is Exhaust Gas Recirculation Insufficient and most likely a loose gas cap.

I get this code on an irregular basis and usually when I over-tighten the gas cap after refueling. The seal inside the gas cap lid can get torqued just right and allow air to bypass which prevents the engine vacuum from pulling enough to sense the tank is sealed, and thus allow the exhaust gas to be pulled into the EGR valve.

Why the guys at AutoZone wouldn't reset it may be because they don't want to assist her with fooling the MVD emissions process, but if you can confirm that's the code she's getting, that's my bet. A new Toyota gas cap would likely fix the problem and I wouldn't give it a second thought while you're away.
 

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