# no codes but MIL on.



## RestoRider/AltimaGXE (Apr 14, 2017)

From what I understand you can get a check engine light even if no codes are on the PCM. I'm currently working
on getting all the little hoses swapped out because from heat and age they are dry rotted. And thus suspect. 
Front 02 sensor changed out and the rear also soon with the help of a shop lift. 

It is possible my Cat converter needs to be replaced. Could be an MFG code triggering but not sure how to read
those. My reader does not seem too selective on those just the DTC.


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## RestoRider/AltimaGXE (Apr 14, 2017)

Got the rear sensor replaced today at my local shop. $20 for labor. So far no MIL lamp
has come up. I did check the system earlier by disconnecting the pigtail at the rear 02 sensor
and checking the resulting code. P0141 (rear o2 sensor fault) 

The rear 02 sensor was the factory unit from 2000 and had the nissan logo stamped into the housing. 
so it had been on board for 97 K miles. The front sensor came out with little trouble. Almost too easy.

I will keep monitoring the situation with followup post on any findings. :laugh:


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## RestoRider/AltimaGXE (Apr 14, 2017)

I hate to bark up my own tree but since nobody else will - here it goes. 

Since the 2 oxygen sensors have been replaced I cleared the code from the rear sensor being
disconnected (P0141) and the logger was showing only 01/01 meaning only 1 code was stored on the PCM
Drove the car today through a mixture of driving scenario's and no check engine light. So it appears to be
out of the woods. Figuring that it had to be a worn component I hit it pretty square on the head. 
Glad I did not have to replace the Cat. Even the A/C seems to work a bit better. Not sure exactly why. 
Whatever I did the car seemed to like it. 

so I replaced 1 PCV hose and both 02 sensors. Like $110 and change for the 3 parts and $20 labor to have the rear
sensor installed. The rest I did myself.


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## RestoRider/AltimaGXE (Apr 14, 2017)

*chasing cats tail ?*

It is a common problem on these cars to suffer from the deteriorating intake manifold gasket. Around the #4 cylinder. 

It is possible I'm in this neck of the woods. It took over 45 minutes of driving to trigger code P0420 This is very similar
to those that have said the manifold gasket replacement fixed all the code issues. I have heard others say you can hear a
very faint hissing sound like letting air out of a balloon extremely slowly. With the engine running at idle. I have heard this
for myself and the sound I get is almost identical in nature. 

I will be performing the carb spray test on the # 4 cylinder area at the intake manifold to see if the leak is there. 

If it comes up a positive I may try a short term fix that will not involve pulling the intake. But would give you
a little more time to deal with the issue and expense. 

again I will post any new findings. :|


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