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940 O2 Sensor Shelf Life?

Lazarus

New member
Joined
Jan 9, 2005
Location
Seattle, WA
Experience needed on this topic. I find a lot of NOS sensors for sale of the type I need. The cost is 1/3 or 1/4th of the new price. Do O2 sensors degrade while they sit on the shelf? Probably a job that you want to do once not twice.

My 940 (Regina) is more sensitive than others and wants to see a swing from 0v to at least 1v, maybe a bit more. Generics don't seem to work well and throw a code.

Thank you!
Lazarus
 
From what I recall. The Regina sensor is a different type and it is very important to buy oem on those. There is no shelf life that I know of. But you never let the sensor wire short to the body of the sensor or ground in the car. That can ruin a sensor.
 
You haven?t had luck with aftermarket, have you tried the NTK brand that many Volvo suppliers sell? I need one for my Regina 740 and wondered about that brand versus oem.
 
There were other cars that used the regina fueling system. You could see what other german GM cars used the fuel system and see if they have a cheap sensor for Regina.
 
Thanks for the comments. Finding various crosses to different manufacturers isn't a problem. They are sort of the same, but not the same. Regina systems are more sensitive than others. The problem is that there are 2 numbers for these parts, just like spark plugs. IPD sells 2 for the Regina: Bosch 109180, and NTK 109467. Both are about $135.00. That's why I was inquiring about whether sensors slowly degrade on the shelf. I don't recall reading any articles about it, but there are plenty about how to change them.

-L
 
Rock Auto has the NTK 25002 for $68, but being rock auto, it may have been kicking around for a while. AFAIK, there's nothing to age in the O2 sensors during storage.

[BTW: never use electronic contact cleaner on O2 sensor connectors - it can get drawn into the sensor and can cause permanent damage.]
 
My 940 (Regina) is more sensitive than others and wants to see a swing from 0v to at least 1v, maybe a bit more.
Not sure how you're measuring, but if you're testing an unplugged Regina sensor and expecting to see voltage of any kind coming from it, you shouldn't. The "standard" style of sensor (Zirconia), as used in the vast majority of cars, generates a varying voltage as it works, usually swinging from 0.2v to 0.8v. Regina cars like yours and mine use the "other" type (Titania), that gives a varying resistance in action. The computer supplies the voltage, and measures how much of a voltage drop the sensor's resistance creates.
 
I've had MUCH better luck with the NTK stuff than a few other brands, both on the Dodge and the Volvo. A friend checked and found a much faster response time and more accuracy on the NTK than the others he had as well.

Also, +1 on no shelf life.
 
Thanks for that added information about the various metals used in sensors. That's the kind of information that most people don't pay attention to. I can't figure out why identical NOS sensors are sold at bargain prices.

Comment on measuring the output of the sensor. The sensor is easily measured with a scope or max/min voltage setting on a digital meter whilst the sensor is connected up normally. I used the official Volvo service manual that shows all the troubleshooting equipment, codes and the various parts of the ignition system. They show a scope picture of the sensor output (after the cat gets up to temperature), and list the actual voltage swing.. typical swings are 0v to1v. My NGK sensor has been puffing along for nearly 15 years with the same voltage swing but recently I started getting some o2 sensor codes..that's why I'm going to replace the sensor as a first step. The only other symptom is higher than expected gas mileage...I absolutely hate the Regina, but oh, well.

-Lazarus
 
There's more to it than just a swing and a voltage range though. The speed that it refreshes can make a big difference. Watching the cycle speed on a Bosch or OEM vs. the NTK, with a scope, the NTK was much faster.
 
I can't recall anything in the 940 manual about this subject of cycling speed. They show the amplitude of the swing. The frequency will depend on the age of the sensor, and the fuel system in the car, along with injector condition, Idle Air Motor condition, Throttle body and intake manifold condition, and overall exhaust setup and condition. 940's don't fall into that sensitive category. My sensor swings from 0 to about 1 volt, which is apparently OK with the computer. Long idle periods or exiting from a multi-level parking garage tend to upset the system temporarily.

-L
 
If you have an older tech or an aging/tiring sensor, your cycle rate may slow as well, due to the sensor being simply slower to react. Watching the output on a scope between multiple new sensors was interesting, seeing the difference in cycle rates.
 
Thanks for your experience on that one. I've never had the opportunity to compare cycling rates using various sensors on the same car, and especially to compare new-to-old behavior using the same sensor part number. I figure if its time to replace the cat, it is time for a new sensor.
-L
 
I think the reaction time decline in a sensor's life is due to contamination reducing the exposed surface area of the solid electrolyte in the sensor. That contamination can gather over many years or in just a few minutes, depending on the source of it.

And yes, the reference air, as little as is needed, can be contaminated whether it arrives at a port on the sensor's rear like the early heated sensors, or through the stranding of the wiring. Example in my experience was the automatic transmission tailshaft seal/bushing leak right in line with the sensor. ATF on the outside of the sensor killed it quickly.

Never heard of contamination arriving on the shelf.
 
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