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Discussion Starter #1
I have recently installed headers and test pipes, and I keep on getting the same code every few days. So I hook up Digimoto to see what it is, it gives me P0420. Does anyone have any input to what this is and how can it be resolved?
 

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Three way catalyst function, bank 1. "Catalyst system efficiency below threshold". That would make sense since you dont have the cats anymore.
 

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Originally posted by BluZee@Dec 8 2004, 01:23 PM
Three way catalyst function, bank 1.  "Catalyst system efficiency below threshold".  That would make sense since you dont have the cats anymore.

Then wouldn't it be ABOVE the threshold? As in really efficient! heh

But seriously nemesis, have you reset your ECU?
 

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Discussion Starter #5
According to sensor readings via Digimoto I feel as if I might have a fouled sensor this is my hypothesis. Bank 1 sensor 1 reading doesnt match the same behavior as Bank 2 sensor 1. I think the voltage should be similar. Though B1S1 only reads half the voltage as B2S1. Maybe my logic isnt right. Any suggestions?
 

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Originally posted by Jetpilot718+Dec 8 2004, 01:48 PM-->
<!--QuoteBegin-BluZee
@Dec 8 2004, 01:23 PM
Three way catalyst function, bank 1.  "Catalyst system efficiency below threshold".  That would make sense since you dont have the cats anymore.

Then wouldn't it be ABOVE the threshold? As in really efficient! heh

But seriously nemesis, have you reset your ECU?

Thats just what it said in the service manual.
 

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hey i justed asked a technician were I work at (nissan dealership) what the code was. He said this the 1st oxygen sensor sends a single to the ECM to tell how much fuel to send to the motor then the 2nd O2 sensor read the fumes coming from the Cat and sends a single back to the ECM
1st 2nd
___/\_____________/\___
/--->--------FLOW--------> \
\______________________/

yes i am bored at work.....shut it

basically he said if you have no cat then that code will come on....I can't explain it for those whos light haven't come on yet...(and they have no cats either)....but that is what the code means

You can reset the ECU but it WILL NOT help at ALL!!!!
 

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Originally posted by LuKsEaZy@Dec 8 2004, 04:06 PM
basically he said if you have no cat then that code will come on....

Kind of like I said? :clap:

Anyone know what I do for a living?
 

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Originally posted by LuKsEaZy@Dec 8 2004, 06:06 PM
hey i justed asked a technician were I work at (nissan dealership) what the code was.  He said this the 1st oxygen sensor sends a single to the ECM to tell how much fuel to send to the motor then the 2nd O2 sensor read the fumes coming from the Cat and sends a single back to the ECM
          1st                    2nd
      ___/\_____________/\___
    /--->--------FLOW-------->  \
    \______________________/

yes i am bored at work.....shut it

basically he said if you have no cat then that code will come on....I can't explain it for those whos light haven't come on yet...(and they have no cats either)....but that is what the code means

You can reset the ECU but it WILL NOT help at ALL!!!!

beat me to it .. good job :clap:

also , your car wont go into a safe mode , so dont worry too much about it..
 

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From what I understand, the 03 won't do this with test pipes, but the 04+ models will . . . thank the lord for my 03!

G
 

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Discussion Starter #13
Thanks for the info. Now that I have a better idea of the problem I wont worry as much. Though its annoying for the light to be on all the time or to have to be reseting it every few days.
 

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Here is a post originally made by Tere on ZCHickz.....might help....

For anyone who is interested, here is the "Atari" method of resetting your ECU -- it also clears the codes if you have a Check Engine Light (CEL) you want to turn off.

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
2. Repeat the following steps (a and b) procedures quickly five times within 5 seconds.
a. Fully depress the accelerator pedal (HARD).
b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 seconds.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.
 

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Originally posted by jinxxycat@Dec 9 2004, 02:07 PM
Here is a post originally made by Tere on ZCHickz.....might help....

For anyone who is interested, here is the "Atari" method of resetting your ECU -- it also clears the codes if you have a Check Engine Light (CEL) you want to turn off.

<span style="color:darkblue">Silly jinxxy, we have that here on Tech too. :nana:

ECU Reset How To</span>
 

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FYI - the OBDII codes are listed here: http://www.infinitihelp.com/Ownership/Common/codes3.htm

Also, if you don't have a Consults tool, you can still clear codes. Using a small screwdriver to turn the diagnostic mode selector switch, located on the side of the ECM/ECU, fully clockwise. After waiting two seconds, rotate the switch to the full counterclockwise position. The diagnosis will end and memory will then be cleared.
 

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Most o4's are LEV certified and have much more sensitive tolerances for emissions.

If your ECU has a letter AND a number on it it is lev.
 

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Your ruining your engine by running it without CATS. Unless you specifically tune you A/F ratio to support this mod you are slowly but surely depleting the life of your motor. Contrary to popular belief the ECU will not re-learn this "cat-less" configuration and adjust the A/F ratio on it's own. You are running the engine much too lean (unless you have already adjusted the correct A/F ratio).
 

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Hope I'm not too new to disagree with someone on this forum but here goes:

Each exhaust bank has two o2 sensors
The front sensor is BEFORE the cat and tells the ECU what the A/F is an is the one the ECU uses to keep the A/F correct when the system is in closed loop.

The second sensor is after the cats and is the one that drives the CEL o2 sensor low threshold code. It's only purpose is to "tattletale" on the Catalytic converter efficiency. It does not have anything to do with managing the A/F ratio.

I have a Dynojet Wideband Commander Datalogger and realtime A/F display on my ATI procharged Z and when the system is in closed loop which is anytime it's basically not close to wide open throttle the A/F ratio stays right around 14.7 and always has no matter what mods have been on the car and even when it was run without the rear o2 sensors in place at all.

It won't damage your motor.
 

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[/quote]

If you have a ATI procharger setup on your Z, then it sounds like you most likely have tuned your ECU/A/F ratio to support your current configuration so that the A/F ratio is ideal (no relation to "catless configuration" above). You say the o2 sensor measures & informs the ECU of the A/F? o2 sensors measure the concentration of o2 and co2 in the exhaust, not A/F ratios (which are mathematically produced by more than one variable within the CPU's of the ECU) which are then relayed to the ECU, which uses these values to compare against predefined tables of values in the ECU EPROM to mathematical vary the A/F ratio in respect to throttle position sensor (all of this is being performed at 0.76 the speed of light). Also how does your rebuttal relate to the "catless" configuration above?
 
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