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Discussion Starter · #1 ·
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

Super Moderator
3,204 Posts
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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