weird code from check engine light?

[Tunerguy1989]

I have the "service engine soon" light on for a while now, I have check the code using my reader and it says p0420 and it reads "catylst level below threshold". Has anyone had a code like this or no what this means. Its my fiances car and her dad said that he had had the catyic converters changed not to long ago so I don't think thats the problem unless there somethin defective.

Theses are the real codes p0420 & p0430 I was way off the first time I made this thread, can someone give me advice on how to fix this problem. It needs to be smogged soon so I'm kinda pressed for time.

Any help would be appreciated it.

[Empty V]

I have the "service engine soon" light on for a while now, I have check the code using my reader and it says p0144 or somethin like that but it read "catylst level below threshold". Has anyone had a code like this or no what this means. Its my fiances car and her dad said that he had had the catyic converters changed not to long ago so I don't think thats the problem unless there somethin defective.

Any ideas I would appreciate it.

I had that code a while ago and I believe it was from the MAF. How many miles does she have on it?

Billy

[Tunerguy1989]

The pathfinder has 155,000 miles and it runs great but it could run better if the ecu wasn't throwing out a code. How did you fix it when you had it?

[Empty V]

Replaced the MAF with a brand new 2001 Maxima MAF. I got it from Victory Nissan online for $89 shipped.

Billy

[Tunerguy1989]

The code is p0422 "exhaust level below thresh hold" is that still related to the MAF sensor.

[Chuck Tribolet]

'01 PF FSM doesn't list code P0422. You sure you got the code right?

[Tunerguy1989]

Ya I'm very positive either p0422 or p0420. But it does say "exhaust level below threshold." Im going to look at the service manuel to see what I can do to fix it but yes im very sure that the code.

[Chuck Tribolet]

There is a P0420 code, problem with the passenger's side cat.

The phrases "exhaust level" and "below threshold" do not occur anywhere in the '01 PF FSM (I used the Adobe Acrobat to build an index of the FSM a while back).


Chuck

[Empty V]

There is a P0420 code, problem with the passenger's side cat.

The phrases "exhaust level" and "below threshold" do not occur anywhere in the '01 PF FSM (I used the Adobe Acrobat to build an index of the FSM a while back).


Chuck

I had the same one, well a P0420. I'm not sure why your search isn't finding it but I know it's there.

[amaff]

Below threshold does for sure. Here's the only thing I could find (from my 03 FSM, but it should be pretty much the same stuff)

DTC No
P0420 0420 (Bank 1)
P0430 0430 (Bank 2)

Trouble diagnosis name
Catalyst system efficiency below threshold

DTC Detecting Condition
Three way catalyst (manifold) does not operate properly, three way catalyst (manifold) does not have enough oxygen storage capacity.

Possible Cause

• Three way catalyst (manifold)
  Exhaust tube
  Intake air leaks
  Injectors
  Injector leaks
  Spark plug
  Improper ignition timing

Basically, if I'm reading this right, the 2nd O2 sensor, whose only purpose is to determine whether or not the Cat is working, is telling the ECU that it's not. So... I suppose to put this in some sort of order of easiest to hardest to fix / troubleshoot, and to some extent, in my opinion, likeliness):

it could be you've blown out your cat (see also: my 03 Pathfinder lol)
it could be that 2nd O2 sensor has failed and is returning bogus values to the ECU
or it could be any number of the reasons above.


Hope that helps

[alexf20c]

i get a "cat below threshold" DTC all the time. i just keep driving and it turns itself off. otherwise, you can disconnect the battery and clear it yourself. it does not hurt the engine; it just hurts mother nature.

the downstream O2 sensors (after the cat) are used to measure catalytic converter efficiency/efficacy. they compare values with the upstream O2S (before the cat) to determine if the cat is working properly.

the downstream O2S is sometimes used to control air-fuel ratio, but ONLY when the upstream O2S is faulty. if you have no other trouble codes, then the only problem is the downstream O2S and/or the catalytic converter. like i said, my pathfinder has been doing this for years now. i just let the ECU rerun the test and hope that it passes (usually takes a day or two), or i manually clear the code with a code reader, or by disconnecting the battery.

[amaff]

When 1/3 of my cat decided it didn't like living in the confines of the cat's shell anymore, I just did the Spark Plug non-fouler trick and it hasn't come back since

[exvin]

I am having the same issue ever since november and no one seems to know what the hell the issue is.

I keep on getting P0304 Cylinder 4 Misfire Detected but three different shops are saying that it comes and goes. Ugh..I dont know what to do about it

[alexf20c]

replace distributor cap and rotor, plugs, and wires.

[Tunerguy1989]

great, thanks for the input Ill proble just replace the o2 sensor. If that doesn't work Ill wait to I get the money and have an exhaust system built for her.

[Chuck Tribolet]

I didn't say P0420 didn't exist. My words were: "There is a P0420 code, problem with the passenger's side cat."

And the '01 service manual does NOT contain the phrase "below threshold". The description for P0420 says "Three-way catalyst function".

[Tunerguy1989]

the downstream O2S is sometimes used to control air-fuel ratio, but ONLY when the upstream O2S is faulty. if you have no other trouble codes, then the only problem is the downstream O2S and/or the catalytic converter. like i said, my pathfinder has been doing this for years now. i just let the ECU rerun the test and hope that it passes (usually takes a day or two), or i manually clear the code with a code reader, or by disconnecting the battery.

Ok so I had the Pathy smoged and it passed no problem, but I had to turn off the light before the test. I had replaced both downstream O2 sensors and it didn't fix the problem would my next step be to change the first O2 sensors or should I just get it diagnosed. The car runs fine I feel like its lost some gas mileage but other wise it runs great I just hate seeing the damn light its annoying. Any other ideas?

[Empty V]

I wouldn't have changed the O2 sensors at all. I say clean your MAF, if that clears it temporarily then it's probably time to replace it.

[Reviresco]

Hey.

Just made a post about this today. Called "Info if throwing P0430/0420 codes."

Give it a read.