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Discussion Starter · #1 ·
Hi everyone,
I just got a CE light, so I went to Autozone to have it scanned. The code that came up was P0400- EGR system. I checked the vacuum lines arround the EGR valve, but everything seems good. The only other thing I can think of is that maybe the EGR valve itself is bad. Are there any other possibilities?
A new EGR valve from Autozone is $120, which seems like a lot. Is there another place I can buy this (if I need to) for less? Oh, and its a 96 Sentra
GXE 1.6l with a 5 speed and 70,000 miles.

Thanks for your help,
Danny :fluffy:
 

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It is possibly a plugged EGR tube between the exhaust manifold and the EGR valve. The tube is replaceable.

There is also a temperature sensor in the pipe between the intake manifold and the EGR valve. If this is defective, it will give P0400.

Lew
 

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Discussion Starter · #3 ·
So which would you do first? How would I know if that temp sensor is bad? I really dont want to invest much in this car, seeing that its rusting, but I do need it. Now if I drive like that with the CE light on, what will happen? Sorry for all the questions
 

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Dandbest said:
So which would you do first? How would I know if that temp sensor is bad? I really dont want to invest much in this car, seeing that its rusting, but I do need it. Now if I drive like that with the CE light on, what will happen? Sorry for all the questions
To check the temperature sensor, remove it and put in a pot of ice water on your stove. Put a thermometer in the water. Connect an ohmmeter to the leads and measure the resistance as you heat the water:

32*F - 7.9-9.7 Megohms (ice-water)
122*F - 0.57-0.70 Megohms
212*F - 0.08-0.10 Megohms (boiling water)

The EGR tube between the exhaust manifold and the EGR valve has a small orifice near the EGR valve which plugs with time. You must remove it to determine if it is plugged. It is very hard to clean since the deposits are quite hard.

If the cause of the fault is not a vacuum leak, it will do your engine no harm to drive with the EGR not functioning. However, it will pollute more nitrogen oxides which are a cause of smog.

Lew
 

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I think there is a Special Service Message for that error code, too. I saw it on ALLDATA, but I don't remember what the SSM was. My CEL came on with the same code and I cleared it, hasn't come back since.
 

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Discussion Starter · #6 ·
lshadoff said:
To check the temperature sensor, remove it and put in a pot of ice water on your stove. Put a thermometer in the water. Connect an ohmmeter to the leads and measure the resistance as you heat the water:

32*F - 7.9-9.7 Megohms (ice-water)
122*F - 0.57-0.70 Megohms
212*F - 0.08-0.10 Megohms (boiling water)

The EGR tube between the exhaust manifold and the EGR valve has a small orifice near the EGR valve which plugs with time. You must remove it to determine if it is plugged. It is very hard to clean since the deposits are quite hard.

If the cause of the fault is not a vacuum leak, it will do your engine no harm to drive with the EGR not functioning. However, it will pollute more nitrogen oxides which are a cause of smog.

Lew
Lew,
Thanks for the procedure! I'll try it out!
 

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Discussion Starter · #7 ·
BIRM_200SX said:
I think there is a Special Service Message for that error code, too. I saw it on ALLDATA, but I don't remember what the SSM was. My CEL came on with the same code and I cleared it, hasn't come back since.
I'll go over to www.alldata.com to see what I can find.

Thanks
Danny
 
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