I took my car to auto zone to get the SES light read and it said Catalst Efficiency Below Threshold in Bank 1. Can anyone tell me what that exactly means???

 

Sounds like a cat failing. Or the O2 sensor. Bank 1, i keep forgetting is that upper or lower.

 

Well my brother is a mechanic , and I dont have the money right now to be going to nissan to get them to diagnose it so I need to know exactly what I need to buy as far as parts go.

 

Well hard to say, its not something I can just throw out there as to what parts to buy since you said you aint got much money. It can be two things, either that O2 sensor is going bad, or the precat is failing.

I could tell you to buy both but if only one is the issue then you just wasted money on the other.

I honestly think it is the precat since it is saying efficieny below. I would test the O2 sensor and see if that is good, if so, then buy a precat.

Dixit

 

1. take it to the dealership and get the PCM flashed. It raises the tolerance for emmissions effeciency for that bank before it'll throw that code again. There's NO charge for that! It's a TSB.

2. spend NO money! You're not there yet. How many miles have you got?

 

Bank 1 is the rear (firewall side) 3 cylinders. There's a pre-cat at the top exhaust manifold and a post cat sensor after the cat.

 

Im not under warrenty any more so TSB isnt free for me anymore.

 

Ill give m some info when I get home...

 

Thanx

 

i got the SAME PROBLEM!!! i brought the car to maximumtuning and autozone..autozone gave me code 0420 and jeffs computer gave the "bank 1 cat" problem. i get bad gas mileage too..like around 16 17 mpg under easy normal driving conditions. i told the nissan guy the code and he wasnt bein real helpful. he said it could be a pipe that costs like $610 or the o2 sensor thats like $130ish
i just wanna know which one it is before i dishout like 800 for this

 

Ok the code P0420 stand for low cat-converter effeciency (bank1) which is the pre-cat by your radiator in the front of the car. I have seen several max's with this code stock or modded. I have this code on my car as well, but I have a reason to have the code. I dont have any pre-cats to be efficient so therefor I understand why my ses light is on. I have used my OBD-II scanner (the autozone method with the flashing light is so ghey ) to pull the code and have cleared it but it will come back on within a few miles.

There is supposivley a recall on this but to be 100% sure about it Ill check my comp at work (AllData) to confirm this but many here have said its a recall. If you search you will find more crap on this code then you want to know, this is like the 30th time its being discussed.

Bottom like is, there is NOTHING wrong with your car. This will not effect power, or driving ability in anyway. The only thing it will effect is you seeing that damn SES light all the time. Ive gotten used to it to be honest, but am at the point were im just gonna yank the bulb out The only thing this will effect other that seeing the ses is if you go to emissions they will fail you just for the SES. You dont have to worry about this til 5yrs after date of purchase (Thats how the laws are here in AZ, I dont know about NY ect..)

To replace this thing is gonna run you near the $1K mark so dont do it unless you have to, the precat assembly is around the $700ish mark plus 1.5-2hrs of labor it will get pretty costly. If your ride is fairly stock they call the dealer near you and have you VIN # near you, and ask if there is a TSB for the pre-cats on an 00-01 max. I still have not confirmed this myself but ill look into it on monday. Still try to give the dealer a call and see what happens.
Keep posted...

 

Bank 1 is the rear at the firewall. That's where the #1 cylinder is.

 

Does not matter. In order for the code to go off nissan is probably gonna try to sell you the whole pre-cat both bank #1 and #2 and cant be bought seperatly. So it doesnt really matter. Just to prove somewhat of a point that this is a TSB, I have an 01 (all 01's are cali spec) so only half a y-pipe can be used. I had the half in for a few weeks and got no ses with one missing pre-cat (the one by the firewall was no longer there) when I got fed up and wanted the whole thing I yanked out the y-pipe and the front pre-cat and gutted the damn thing and that was when I got the code for PO420 coincidence?
Now the thing is for MY car there are only 3 o2 sensors. There is on upstream o2 be4 the front pre-cat (be4 the pre-cat by the radiator) and one down stream driectly after the front pre-cat. As far as the other pre-cat (near firewall) it has only one o2 which is an upstream but has no downstream so even if that pre-cat was gutted the ECU would not register it as it not being efficient since it had nothing to track its be4 and after. Id does however track the one by the radiator with both upstream and downstream, directly after I gutted the front the light went on a few miles later down the road.
So either bank 1 is the one near the front of the car (does not necessarily have to be on the side of #1 cylinder, but doesnt mean it cant be) since my SES went on after that side was gutted OR it was just a coincidence the light went on after I gutted it and its actually a TSB. Your call, I belive what I know but if im wrong then so be it.

 

Maybe I'm wrong as well...I had a PO420 on my `01 and it had 4 O2 sensors. It does matter, though....to me. I take a different approach...concerning dealerships. I will not go there unless it's a warranty issue, and if I do, you'd better believe that I have pulled out my oscilloscope, digital multimeter and anything else that I have to troubleshoot it. I haven't seen the dealership yet...but if I do, I won't get charged diagnosis time for a cat that's under warranty - for instance, or an O2 sensor that's not under warranty that I know is good.

There are a lot of good honest mechanics out there. Conversely, there are a lot of rip off artists....and it only took me one time being ripped off, to become sceptical of them all. The one that screwed me, destroyed my `88 SE....so all that to say, it's pays to know.

 

i think im gonna just give the car to jeff and let him to try figure it out. im gonna change out the o2 sensor first...that damn pipe costs too much..but if the ecu throws a code afterwards..i might just change that too..

 

Thats odd about the # of o2's. Dont get me wrong though, I dont take mine to the dealer unless I have to either. I resurfaced my rotors myself when they warped, then only time I took it was for the wind noise TSB and after I got it back they has conviniently curb rashed two of my rims for me and to make it worst it was on the passenger side so I didnt see it til I got home.

Rip off artists is an understatment, there are MANY out there. I for one am NOT one of them and will never be. I honestly do not care about the P0420 code because I know there is nothing wrong with my car. As far as Im concerned the SES went on due to the gutted cat Even if I go they are gonna blame it on my exhaust so whats the point. Luckily for me I have access to almost all the tools I need to work out any problem I have.

The things is Nissan has a diff ECU there, its called the Consult-II
which only nissan reps are allowed to have. I cant buy that, and thats the tool that I need to erase this code perminently. It costs apprx $5K but then again most hand held ECU type tools do.

Bottom line, I dont blame you for feeling that way. Alot of techs out there are ripping people off left and right, that how they grow into chains. Nothing you can do about it, I see it every day.

 

I've got the 420 code for the same reason as hitman as you can tell from my mods. It has no effect on ANYTHING in the car. It is merely an indication that there COULD BE an emissions problem. I really wouldn't bother fixing it.

If you have an 02 sensor problem, I believe there is a separate code for that.

 

There is no emissions problem. Most 4th gens with a y-pipe and a cat can pass emissions with ease. The pre-cats do the same thing as the cat does, only faster. The cat takes a few min be4 it fires up and starts to reduce emissions since its a few ft away from the engine. The pre-cats however are directly below so they fire up right away. All this accomplishes is reduced emissions at start up while the cat is still code.

Edit: Actually I 4got to mention, they wont pass you with an SES light on But actually your emmissions readings should still allow you to pass.

 

You are correct - it does not mean there is a problem. What I meant to say is the code signals a potential emissions ISSUE. But even if the condition is present it will have no effect on performance, mileage, etc.