Emissions obd testing problem, check engine light
1996 Nissan Maxima

Emissions OBD testing problem, check engine light

(1996 Nissan Maxima)
Check engine light on, solenoid purge valve (from Nissan) replaced, then car driven appr. 45 minutes (65 mph), check engine light off then back ON!
How can OBD system indicate some other problem, and could it be a problem with computer (OBC) itself?!
(1996 Nissan Maxima must pass smog inspection.)
What seems to make the problem better or worse? Unknown - check engine light on, solenoid purge valve replaced, light still ON
How long have you had this problem? Approximately 3 weeks
Tags: nissan, maxima
1 answer & 5 comments
Popular Answer
on November 12, 2019

Perhaps the actual failure has not been repaired - yet.
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on November 12, 2019
Since on-board diagnostics can't pinpoint the actual problem, can an emissions test site show problem? Or, should I go to Nissan dealer to see if they have more detailed diagnostics than my mechanic.
on November 12, 2019

It is likely the purge valve was replaced based solely on the diagnostic trouble code.

Subsequent *hands-on* testing must follow code retrieval to confirm what the actual failure is..

Many times the sensor gets blamed mistakenly when it’s just doing what it is supposed to do - report a problem within a particular system to the control module - which turns the light on.

Of course I can’t determine what has taken place here exactly - can only make a best online guess.

Perhaps you could quiz your mechanic further.

Good luck!
on November 12, 2019
Thanks for your replies and comments. The fault code was reported as PO443 (emissions). I'm not certain what "hands-on" testing is, or what is involved, and possible cost.
on November 12, 2019


P0443 NISSAN Possible Causes:

EVAP control system pressure sensor
Damage harness or connectors to the Purge Control Valve
The valve circuit is open or shorted
EVAP canister purge volume control solenoid valve may be faulty (The valve is stuck open)

This is an example of what needs to be tested .. I can’t elaborate on the cost - too many variables.
on November 14, 2019
More thanks. The purge valve was ordered from Nissan as replacement part, and the repair shop is highly rated and listed @ this web site.
I would HOPE that the mechanic checked everything related to this after replacement.
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on November 12, 2019

Perhaps the actual failure has not been repaired - yet.
Sign in to reply
on November 12, 2019
Since on-board diagnostics can't pinpoint the actual problem, can an emissions test site show problem? Or, should I go to Nissan dealer to see if they have more detailed diagnostics than my mechanic.
on November 12, 2019

It is likely the purge valve was replaced based solely on the diagnostic trouble code.

Subsequent *hands-on* testing must follow code retrieval to confirm what the actual failure is..

Many times the sensor gets blamed mistakenly when it’s just doing what it is supposed to do - report a problem within a particular system to the control module - which turns the light on.

Of course I can’t determine what has taken place here exactly - can only make a best online guess.

Perhaps you could quiz your mechanic further.

Good luck!
on November 12, 2019
Thanks for your replies and comments. The fault code was reported as PO443 (emissions). I'm not certain what "hands-on" testing is, or what is involved, and possible cost.
on November 12, 2019


P0443 NISSAN Possible Causes:

EVAP control system pressure sensor
Damage harness or connectors to the Purge Control Valve
The valve circuit is open or shorted
EVAP canister purge volume control solenoid valve may be faulty (The valve is stuck open)

This is an example of what needs to be tested .. I can’t elaborate on the cost - too many variables.
on November 14, 2019
More thanks. The purge valve was ordered from Nissan as replacement part, and the repair shop is highly rated and listed @ this web site.
I would HOPE that the mechanic checked everything related to this after replacement.

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