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Q:

failed smog test on 1995 Ford Aerostar

Master 77c385ec3dad981443cd9a5b509db22a5a3fa078fc8c154e2bda5f4630ddae75
my 4.0 aerostar has exsessive n. o. reading.i changed the mas sensor and the check engine lite is now out.what other repairs should i do before i retest it?
(1) Answer
(1) Comments
the mass air flow controls hc and co. nox is controlled by egr and cat converter. you had more than one problem. have these 2 items checked for operation

Roy
thanks for your reply.i was hoping not to replace the cats as they are high dollar.ill change the egr and see what i get.if it still wont pass ill have to take it to the referee.