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Old 05-28-2004, 07:25 PM   #16
wolfman
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Join Date: Jun 2002
Location: Texas
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OBD2 cars (96' and UP) Monitor EGR and O2 function MUCH more closely than OBD1. An OBD2 PCM can not only control EGR function, it can actually SEE how far and fast/slow the EGR is or is not opening. Likewise O2 sensor function is very closely monitored and most OBD2 Saturns have 2 O2 sensors, including one that helps monitor catalitic convertor function. If an OBD2 car has an EGR VALVE related problem it WILL set a code 99.9% of the time. Likewise an failing O2 sensor (or even a marginal one) will set an SES light on an OBD2 car nearly 100% of the time (and often when the O2 sensor is still pretty much just fine but is being adversely affected by another system or sensor) Even on OBD1 cars there is NO "recommended change interval" for an O2 sensor. You replace them when they fail badly (and often) enough to affect either emissions or driveability, thats it. Believe it or not, factors such as ambiant air temperature, quality of fuel and even humidity alone or in combination, can have TEMPORARY adverse affects on O2 sensor readings, that will self correct when the "factor" goes away.

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Old Saturns never die, people KILL them, so check your damn oil!
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