Volvo RWD S90-V90 Forum

INDEX FOR 10/2025(CURRENT) INDEX FOR 9/2004 S90-V90 INDEX

[<<]  [>>]


THREADED THREADED EXPANDED FLAT PRINT ALL
MESSAGES IN THIS THREAD




  REPLY TO THIS MESSAGE    PRINT   SAVE 

What Voltage Should Rear O2 Sensor Read? '97 960 S90-V90

posted by  WrenWright on  Sat Jan 25 21:39 CST 2014
Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
last visit: Mon Oct 20 07:51 CST 2014
[RELATED]

One my scanner, my rear O2 sensor is reading 0 volts consistently. From what I've read, the front sensor should fluctuate between .2V and .8V or so, which it is doing. However, regarding the rear sensor, I've come across some conflicting information. I've read that it should be a steady ~.4V but I've also read that it should be 0V unless something is out of whack with the Catalytic converter.

I've got a constant PO172 code; the check engine light comes on occasionally but then goes out. From what I've been reading, that is from a vacuum leak of some sort, although I can't find one.

I'm thinking that I've got a dead rear O2 sensor. I checked the connector and everything seems to be OK. The car runs fine and gets good gas mileage.

What sort of voltage should I be seeing from the rear sensor? If the sensor is dead, would that give the engine code that I'm seeing? Thanks!







  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    What Voltage Should Rear O2 Sensor Read? '97 960 S90-V90

    posted by  Will740turbo on  Mon Jan 27 02:28 CST 2014
    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
    last visit: Wed Oct 22 16:09 CST 2014
    [RELATED]

    I'm not sure on the exact spec, but it being constant makes sense, assuming the other O2 sensor(s) are working.

    If it's old, it would be good to replace it. Either way, if you remove it or otherwise introduce fresh air into the tail-pipe, it should produce up to 1V when there is no O2 in the exhaust, and 0V when there is atmospheric oxygen level in the exhaust. The O2 sensor pits outside air against air in the tailpipe, and an imbalance one way or another will produce a voltage.

    O2 sensors wear out eventually, or the port to outside air can be blocked (by soldering the connections, for one!), or the port to the inside air can be blocked by soot/particulate, or the heater or sensor circuitry can fail.


    This page might be useful for your elucidation. http://www.therangerstation.com/tech_library/O2Sensors.htm








  •   REPLY TO THIS MESSAGE    PRINT   SAVE 

    What Voltage Should Rear O2 Sensor Read? '97 960 S90-V90

    posted by  hf63 on  Sun Jan 26 13:18 CST 2014
    Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
    last visit: Wed Oct 22 15:19 CST 2014
    [RELATED]

    I am not sure about the voltage but if the sensor is original or over 10 years old I will just replace it. The best prices for this sensors is Amazon.

    I normally just check the resistance if open, replace it!!

    You can check for vacuum leaks using a vacuum gauge and some carburetor spray.

    Speedy







<< < > >>



©Jarrod Stenberg 1997-2022. All material except where indicated.


All participants agree to these terms.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. or Ford Motor Company. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.