# 1993 Altima failed NOx smog test



## altatension (Jul 3, 2008)

Bought ($10, a gift) a 1993 Altima with 198K miles.

Drove it for 50 miles and then took the smog test:

15 mph CO2 .3, HC 63, CO .33, NO 923 (failed - max 701)
25 mph CO2 .2, HC 48, CO .23, NO 535 (passed - max 730)

All test were passed with the exception of the NOx.

Since this was a test only station they provide little help as to what to
do. A 2004 thread from this forum suggests that the problem resides in the
EGR system:

EGR tube plugged or O2 sensors or timing or manifold passages.

Does this sound right? do I need a mechanic to do it (I have basic tools).

Any help is appreciated


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## Asleep (Jan 19, 2003)

locate the egr backpressure transducer. its the other gold thing next to the egr valve. now, directly on the bottom of it, theres a hose there that sends its signal to the egr valve - pinch it. if it feels gummy and soggy, replace it. ill bet its got a hole in it or its collapsed on the inside. id say about 99% of the nissans ive dealt with that didnt pass emissions, had a problem with this hose.


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