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Discussion Starter #61
Ordered the correct part from nissanpartsdeal and it arrived today. Box says Nissan Group Genuine Parts, 25080-89907. (https://www.nissanpartsdeal.com/parts/nissan-sensor-temperat~25080-89907.html?Make=Nissan&Model=Altima&Year=1995&Submodel=&Filter=()&Location=body_electrical/electrical_unit,,25080X) Out of the box and into boiling distilled water in a stainless pot held by stainless forceps. In boiling water for 4 minutes, it only comes down to 94.9 Ω. It will be going into the car tomorrow. Caveat: I haven't seen any of these sensors get down to 21 Ω-24 Ω as described by the service manual.
I'm disappointed the new Nissan sensor only goes down to 94.9 Ω in boiling water, 100°C. Just now on the table it measures 1.62kΩ @ 62°F and yesterday measured 1.3kΩ @ 68°F and 94.9 Ω @ 100°C. I'll take it outside and place it on the cold engine block and later when they've equalized I'll measure while disconnected. If both cold and hot resistances are very similar and if the ZR4 hasn't seen any new codes set, then why change? The one that's in there now would go to 80Ω @100°C and is years old. Although the first time I drove after replacing the 'original' years old back and repairing the connector I got a code P0125 coolant sensor but no check engine light. I reset the code and have been driving for a week no check engine light. I'll check for codes now with the ZR4 which reads the P0125 as an O2 sensor rather than the coolant sensor. The problem that I see with the sensor at 80Ω instead of 21Ω-24Ω@100°C is that the temperature gauge might read in the safe zone instead of in the overheating zone. If it read overheating at the proper temperature then one might shut down in time to prevent heat damage to things like the internal distributor seal. It would seem like the kind of sensor resistance change that would sell more replacement parts. I do note that the ECM sends different voltages to the sensor as temperature changes. Someone might argue that at 100°C the ECM is sending a voltage higher than my meters provide in resistance check and that the higher voltage increases current flow causing internal heating of the sensor that won't occur with my resistance measurement meters.
 

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Discussion Starter #62
If I were in a lab I'd put the sensor in boiling water, put a .1Ω precision resistor in series, then record the voltage across the precision resistor to calculate current and measure the voltage across the sensor while raising the voltage in steps across the sensor in boiling water.
 

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Discussion Starter #63
Change of plans. I'm not changing out the years old 'original' sensor. I just check the cold engine off with the ZR4 and there are no codes set from the week of driving. There is one green/red LED that I know will go green when I check the codes with a hot engine. I'll keep the $32 sensor a few more days and return before return expires, if all stays good.
 

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Discussion Starter #64
Okay, car runs and no codes set but the ZR4 reports a red led for EG or EGR valve. So, a new EGR valve it is.
 
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