zman187

Hey everyone have posted for a while but just a quick question, maybe someone could help....my check engine light came on a month and a half ago I would say....and I disconnected the battery. So time went on and then maybe 2 weeks later it came on again.. and ever sense then it comes on every 50 miles or so.. I invested in a OBD 2 reader a couple day ago...I read the code and it read "Catalyst System Efficiency Below Threshold (Bank 1)." Does anyone have any idea what that means, because I know I don't. Thanks for the help.


z

zman187

no one has any idea on this?

MaximaMan77

It either means the precat for that bank has gone bad or the O2 sensor is bad.
How many miles do you have on the car?

Todds_max

Zman,
The short version is.... OBD-II systems use an o2 sensor before and after each catalytic converter. The first sensor is typically responsible for adjusting A/F ratio and the second sensor monitors the converter’s efficiency. The ECM is continuously monitoring the results of each and over time determines how effective (efficient) the converter is. Your ECM has determined one of your converters is failing. A mis-tuned engine can damage a converter quickly. It's probably not something you are able to fix yourself. Not becuase a converter is impossible for a DIY'r to replace, you just want the correct diagnosis. You should probably visit your dealer... be prepared... converters are expensive.

zman187

do you think a intake could have done this???? and is this really going to hurt the engine...I dont have much money so I can't be wasting it on sensors acting up on me

I have 52700 miles on the car

Colonel

Also check into the TSB about this. IIRC, ON the earlier models, the Cat/o2 specs where WAY to close and it requires a ECU reprogram to "expand" the tolerances.

OR, you really have Emissions failure. I would make sure to check up on that TSB.

Good Luck

MaximaMan77

Intake, not directly. The main thing that kills cats is running rich and or to much heat. The intake would lean you out just a bit but the ECU should correct it based on the readings from the O2 sensors.
I would have your problem diagnosed and refuse service if it's a O2 sensor, you should be able to do that yourself. If it's a precat that job is a bit tougher if you think you can hack it give it a go. Once you know for sure what the problem is you can get either part from DAVEB at a much better price than at a dealer.

zman187

Maximaman,
I went to the TSB website and I found this...
Make : NISSAN Model : MAXIMA Year : 2000
Service Bulletin Num : NTB00070A Date of Bulletin: MAR 15, 2001
Component: OTHER
Summary:
SOME VEHICLES MAY EXHIBIT A MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P0420 (THREE WAY CATALYST FUNCTION) STORED IN THE ECM. *TT


tell me what you think by the way when you read the codes you just get the number part and my code was 0420 thanks

zman187

MaximaMan77

I'm not familiar with the TSB's for 00&01 Max's. Even if this TSB applies in your case you will still need to take it to a dealer. They will then diagnose it and call you with the results. Just try to see if the TSB does in fact apply and whether or not the emissions related parts fall under warranty. This will be the most cost effective way to go about it. Just make sure they don't do any work until you've given them the ok.
You see if the TSB applies the they reflash the ECU and your done (I guess) if it's the precat it needs to be replaced, if it's the O2 sensor it needs to be replaced or it could lead to other problems. Some of the NJ boys should be able to lead you to a good dealer. Just remember to put your stock intake back in.