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I think I replaced it about a year ago,,It shouldnt be bad that fast?
I wonder how to test it??
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I’m not sure if it will be much help for you, but the FAQ’s make for good reading:
https://www.brickboard.com/FAQ/700-900/EngineSensors.htm#OxygenSensorLifeandDiagnostics
--
Any twenty minute job is just a broken bolt away from a three day ordeal
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Almost all dealers were out of stock !!
just kept looking using the part #
I finally flound 1 for $26!!!
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Stockwise claims Bosch is OE for a 1993 940. I don't know if you have a turbo or Regina car but they show both versions. Both are pricier than what you found but they might last more than a year.
https://www.stockwiseauto.com/auto-parts/emission-control/sensors/oxygen-sensor?Year=1993&Make=Volvo&Model=940
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loose connection at header caused o2 sensor to run rich,that caused multiple other problems that turned out to finally be a clogged cat!
Also I found a cheap source for new IAC valves that fit on 940s w regina system,.$28 on ebay,,for Vw Jettas!!sent a message about Fuel Injection Idle Air Control (IAC) Valve For VW Volkswagen Jetta Golf EuroVan #223550043242
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bosch is 2 wire,,,NTK is 3 wire,,,, mIne is a base regina NON turbo..
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I believe you'll find that both the NTK Regina and Bosch LH2 O2 sensors are all heated and thus all use 3-wires. Unheated 2-wire sensors date quite far back like into the early 1980s, possibly K-Jet (Art would know, I'm too lazy to check).
The Volvo service green manual wiring diagrams for both Regina and LH2 show the heater circuit on the 2-pin connector plug white wires (the Bosch standard) with one white wire as the ground (doesn't matter which one). The sensor circuit is the black wire with the signal. Ground for the sensor circuit is shown as a coax-type shield on the black wire (becoming a shielded green wire at the firewall), with one end of the shield to the O2 sensor body (exhaust system) and the other end of the shield to chassis ground at the ECU. If there happens to be no shield then presumably for signal ground it's either depending on the exhaust system as chassis ground or else there'd be a 4th wire, which you may find in some universal sensors.
There was considerable argument here once that the sensor got a trickle of air as atmospehric O2 reference through the cable sheath or wire insulation, but that doesn't at all make sense to me and if there's any truth to this then it likely only applied with the earliest generations of unheated sensors.
There's also been considerabe discussion of not using dielectric grease with O2 sensors. It is generally not recommended for the O2 sensor circuit (the heater circuit doesn't matter), not because it might melt and block off atmospheric reference (or trickle down inside the wire to get inside the sensor head as some postulated) or because it's an electrical conductor (which it isn't), but rather it can contain impurities or attract contaminants that might be conductive and have some affect at the millivolt level. Waterproof crimp connections are the preferred choice and Bosch supplies these with many of their universal sensors. I don't know about NTK.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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I believe you'll find the two Bosch O2 sensors you mentioned on StockwiseAuto are both for the Bosch LH 2.4 fuel system, not Regina. One is for LH turbo, one for LH non-turbo. The difference is just the length of the cable owing to the different locations of the O2 sensors on the exhaust. The other Bosch sensor listed there is a generic 3-wire fitment without the connectors for all LH 2.4 applications. The generic is the exact same 3-wire sensor head and for a lot less $ if you're willing to do a proper moisture proof splice using the old cable. This is well worth knowing as the O2 sensors with the proper cable and connectors are often hard to source or even NLA, so the generic fitment is a perfectly suitable and economical alternative. The Bosch Auto Parts website lists the associated part numbers and fitments for the various LH years.
As for the Regina fuel system being discussed here, the correct fitment is the NGK 25002 listed further down on StockwiseAuto. NTK is a division of NGK (the sparkplug people) so you may see either name listed. It's not clear from my reading if NTK was the actual OEM for Volvo, but they may well be. NTK is a major manufacturer of OE O2 sensors so you should expect top quality.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Dear Chris Mullet,
Hope you're well and stay so. The NTK #25002 (Volvo #3517394) oxygen sensor is correct for a car with the Rex-Regina fuel/engine management system. I believe NTK was an OEM supplier to Volvo.
A Bosch Oxygen sensor will work on '93 models, but only those equipped with the Bosch fuel/engine management system.
Bosch sensors for the 1993 models have two wiring connectors. For the 1994 and 1994 models, that use Bosch Oxygen sensors, there's a single connector.
Hope this helps.
Yours faithfully,
Spook
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Spook, thanks for clarifying. I had always assumed Bosch was the O2 sensor supplier for both the turbo and Regina 740/940 cars, with the Reginas using the loooong-life titania type. We drove our 1990 740 Regina for many years and many miles and never had an issue with the O2 sensor so I never had the need to remove it and see who’s name was stamped in it.
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Interesting concept that Bosch might have supplied the titania sensors. I would be very skeptical Bosch supplied anything for Rex/Regina engine management unless my theory is hogwash that Volvo used Bendix as a second source for a few years to avoid total dependence on Bosch. I'm betting NTK was the OE mfr of the oxygen sensors for those cars.
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Art Benstein near Baltimore
"A harmonica plays better too, once you learn to keep the slobber out!" -machine man
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Here's an interesting thread in the TB archives that includes mention of the differences between the Bosch sensor used with LH systems and the NTK sensor used with Regina
https://forums.turbobricks.com/showthread.php?t=286348 How to measure O2 signal for Regina
Seemingly a significantly different techonology used, with the zirconium Bosch generating variable voltage for the LH system while the titanium NTK design provides a variable resistance for external voltage with Regina.
Noted in that thread is measuring voltage in circuit and the slightly different operating voltage ranges for the two designs. Clearly you need a good meter to get half-accurate millivolt readings, not some $10 special. Some guy who was apparently obsessed with clean flame traps was part of that conversation (lol).
Note to the OP, Peter, regarding premature O2 sensor failure, in that thread it mentions what I was going to suggest
100,000 miles, O2 should be changed...if engine consumes oil thru exhaust pipe, it won't last long
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Hey Art!
You are roaming like me!
I think we of the BRICKBOARD understand the “end game” with Bosch or any other supplier.
That’ll be to make them all different despite the making all the sensors operate in the same way of creating a signal so close to each other.
The only change is in the boxes they come in.
Just as different as the computer boxes are on the outside with on going fixes in progress.
As you probably know in electronics circuits they can be nearly the same but the components are subject to price and quantity too! The adage is, it’s the same result but different or Two roads to the same places depending on which side of the road you are on?
Add a heater or not to have a heater for lots of extra bucks! The love of dealership markups and bidding among their vendors runs deeper than we can imagine. Every car sold sells more parts!
The head end of oxygen sensors are too identical to be a coincidence!
If you think there is a great difference in the manufacturers costs for these things, think again as the connectors are just as cheap!
Yes, Bosch bought lots of the beginning ideas of fuel injection from Bendix. The early setups filled the whole back seat. Bendix, Delphi and Delco are still big contenders and rub each other’s backs occasionally! In fact, it’s all a global market now!
Would surprise me that since the sensors screw in that they are interchangeable in function.
Phil
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“… I would be very skeptical Bosch supplied anything for Rex/Regina engine management..,”
I don’t know about the O2 sensor on Regina cars however I know the coolant temp sensor was Bosch as I pulled it out once to test the resistance.
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