Hey guys my fzj80 has a p0401 code. I wanted to fix it myself, but did not have the time so i brought it to a shop. Got the truck back and it still had the code and o2 sensor codes. They said the exhaust needed to be fixed for it to go off. I did the exhaust myself, which involved a clamped sleeve, but shes pretty darn quiet. The o2 sensor codes went away but not the 0401. Brought it back theyre saying the catalytic monitor is not clearing. Theyre saying the cat is good, but needs to have all leaks in the exhaust to go away because the cat is not getting up to temperature. Does this sound correct or might there be more involved then patching a very small leak? Thanks
P0401 error code exhaust cat relationship (1 Viewer)
- Thread starter Rhino5000
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are you running both cats?
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Theres 2 cats in the exhaust system if thats what you mean. The mechanic was not clear as to which one was "getting up to temperature " . Theres 2 o2 sensors also. One is just before the first cat. I think the second is in between the 2 cats
so if you are post 94 your cats are in series and there are two o2 sensors one pre-cat and one post the second cat. my guess is that the second cat would be the culprit for not coming up to temperature. check the joint between the two cats for leaks or anything from the second cat to the second o2 sensor. for what it is worth, I run only one cat and don't have any issues with it.
From my experience those 2 errors are not related.
401 is EGR and usually caused by bad modulator, vacuum lines and temp sensor, sensor just need a cleaning with a wire brush.
O2 should be replaced at this age but can try a thorough cleaning first. Easy to do, just 2 nuts each.
401 is EGR and usually caused by bad modulator, vacuum lines and temp sensor, sensor just need a cleaning with a wire brush.
O2 should be replaced at this age but can try a thorough cleaning first. Easy to do, just 2 nuts each.
I have a similar problem. I had intermittent loss of power that ended up being clogged/old cats. I cut them out and straight piped it for now, along with new O2 sensors. The codes from the sensors cleared but still have an 0401 hanging around. Not 100% certain if replacing the cats would fix the code or if it's tied to something else EGR related like Qball said.
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The P0401 is an EGR code, has nothing to do with the cats. Depending on your emission requirement, the easy way to "fix" is to unplug the EGR temp sensor and put a 4.7K ohm resister across that connection.
What is exactly happening with the "Fix"? It it just giving the ECU what it wants to see from the EGR? A normal operating status.
Will the resister for P0401 "fix" the CEL for smog compliance? Cruiser will pass emissions if the CEL is reset right before the test. Is there any long term issues running with a P0401? Asking for a friend....
ALSO, what wattage on the resister?
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Yep.
That will depend on "smog compliance". It will show not ready on the EGR, here, we are allowed two not ready, so good to go. If it passes just after clearing (would be not ready) chances are good.
Doesn't matter, 1/4watt or whatever is handy. Crimp on a couple of .110" female spades, plug it in and tape up, no more code. Mine still has the EGR kinda working, some we have plugged the lines, BBs, others have gone to the work to remove the whole thing.
Dustin Messina
SILVER Star
The 401 code is the devil. I pulled my upper intake cleaned it, replaced everything inside of of the ERG system, cleaned everything and still have the damn code. Only went away with I jumped it with the resistor. Not a fix, but got rid of the light. No emissions checks in Mississippi.
Thank you for the clarifications!Yep.
That will depend on "smog compliance". It will show not ready on the EGR, here, we are allowed two not ready, so good to go. If it passes just after clearing (would be not ready) chances are good.
Doesn't matter, 1/4watt or whatever is handy. Crimp on a couple of .110" female spades, plug it in and tape up, no more code. Mine still has the EGR kinda working, some we have plugged the lines, BBs, others have gone to the work to remove the whole thing.
