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OBD app won't detect front o2 sensor

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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RaydenOBD
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Year and Model: C70 2.4T MT 2002
Location: Marmande

Re: OBD app won't detect front o2 sensor

Post by RaydenOBD »

Still searching .. that makes no sens, just like if my o2 sensor was invisible to OBD apps, also tried switching ISO didn't make a difference.

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xanthefin
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Post by xanthefin »

I am gonna leave this now as boring technical information which i did end up confirming now too with on my bench ME7 ECM.

Screenshot_20240523_231253.jpg
Screenshot_20240523_231253.jpg (63.02 KiB) Viewed 1211 times
ME7 Volvo (not all?.. all? i dont know) ECM only shows PID 15 Aka Oxygen Sensor 2 registered for Standard OBDII Emission data even though shows for two Sensors to be present so no PID 14 Front Oxygen sensor reading for this Standard OBDII way.


.. but after little accident i found how to make natively ELM327 talk Live Data finally with CAN Bus very flawlessly on P80 and P2 systems so now after couple days work included ME7 in there as starters.
Screenshot_20240523_214635.jpg
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ZionXIX
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Post by ZionXIX »

xanthefin wrote: 24 May 2024, 08:22

.. but after little accident i found how to make natively ELM327 talk Live Data finally with CAN Bus very flawlessly on P80 and P2 systems so now after couple days work included ME7 in there as
Xanthefin, Im trying to use the app to read O2 sensor voltage as well as fuel trim to better diagnose my oxygen sensors. Is the OBD-II capable of reading this on a 1996 850 turbo? I haven't found a way to see that yet.
Scarlett: 1996 850 Turbo Wagon in Reagent Red Pearl ~210K mi
Norman: 2012 F150 XLT Crew Cab in Oxford White ~110K mi
Ember: 2005 XC90 2.5T FWD in Ruby Red Metallic ~83K mi *Newest addition to the fleet*
Ruby: 1997 850 Turbo Wagon in Reagent Red Pearl - parts car
Rose: 2020 Ram 1500 in Delmonico Red Pearl - SWMBO's Vehicle

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xanthefin
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Year and Model: 1997 850
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Post by xanthefin »

ZionXIX wrote: 08 Jan 2026, 10:44
xanthefin wrote: 24 May 2024, 08:22

.. but after little accident i found how to make natively ELM327 talk Live Data finally with CAN Bus very flawlessly on P80 and P2 systems so now after couple days work included ME7 in there as
Xanthefin, Im trying to use the app to read O2 sensor voltage as well as fuel trim to better diagnose my oxygen sensors. Is the OBD-II capable of reading this on a 1996 850 turbo? I haven't found a way to see that yet.
Sorry much of late reply. I was actually in Japan when this was posted.

On 850 if its Motronic M4.4 yes it has both Lambda Voltages and Fuel Trims but M4.3 not with App sadly due how it talks.

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ZionXIX
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Post by ZionXIX »

xanthefin wrote: 20 Jan 2026, 20:20
ZionXIX wrote: 08 Jan 2026, 10:44
xanthefin wrote: 24 May 2024, 08:22

.. but after little accident i found how to make natively ELM327 talk Live Data finally with CAN Bus very flawlessly on P80 and P2 systems so now after couple days work included ME7 in there as
Xanthefin, Im trying to use the app to read O2 sensor voltage as well as fuel trim to better diagnose my oxygen sensors. Is the OBD-II capable of reading this on a 1996 850 turbo? I haven't found a way to see that yet.
Sorry much of late reply. I was actually in Japan when this was posted.

On 850 if its Motronic M4.4 yes it has both Lambda Voltages and Fuel Trims but M4.3 not with App sadly due how it talks.
I believe I have the Motronic 4.3. How do I see O2 sensor numbers?
Scarlett: 1996 850 Turbo Wagon in Reagent Red Pearl ~210K mi
Norman: 2012 F150 XLT Crew Cab in Oxford White ~110K mi
Ember: 2005 XC90 2.5T FWD in Ruby Red Metallic ~83K mi *Newest addition to the fleet*
Ruby: 1997 850 Turbo Wagon in Reagent Red Pearl - parts car
Rose: 2020 Ram 1500 in Delmonico Red Pearl - SWMBO's Vehicle

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xanthefin
Posts: 444
Joined: 4 May 2019
Year and Model: 1997 850
Location: Pluto
Has thanked: 106 times
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Post by xanthefin »

ZionXIX wrote: 20 Jan 2026, 21:27
xanthefin wrote: 20 Jan 2026, 20:20
ZionXIX wrote: 08 Jan 2026, 10:44

Xanthefin, Im trying to use the app to read O2 sensor voltage as well as fuel trim to better diagnose my oxygen sensors. Is the OBD-II capable of reading this on a 1996 850 turbo? I haven't found a way to see that yet.
Sorry much of late reply. I was actually in Japan when this was posted.

On 850 if its Motronic M4.4 yes it has both Lambda Voltages and Fuel Trims but M4.3 not with App sadly due how it talks.
I believe I have the Motronic 4.3. How do I see O2 sensor numbers?
I think this ECM has been touched best by rkam as this falls under older diagnostic protocols.

But if you are in old ways are best and insist manual labour.. and you are radio amateur who knows morse code.. you are in luck!


You need transfer ECM into DTM 4 mode by shorting Pin with button # 3 in OBD port to GND 4 times. (this is by other manual DTM 3 so 3 times so Volvo is not sure how document this)
Now communication is at rate of x10 so you need be quick reading angrily flashing led light (OBD Port Pin #3 is + and use GND Pin # 4 or 7) and input commands with button you used in previous step.

Next you need know command but if it would be same as Fenix 5.2 then in theory you need quickly input value 53 in decimal so press button exactly that amount in a second!

The now you should get back 8 bytes of data which in theory is what you looking for the value.


..or get Volvo VST handheld device i am sorry.

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ZionXIX
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Year and Model: 1996 850 Turbo S/W
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Post by ZionXIX »

xanthefin wrote: 21 Jan 2026, 16:23
ZionXIX wrote: 20 Jan 2026, 21:27
xanthefin wrote: 20 Jan 2026, 20:20
Sorry much of late reply. I was actually in Japan when this was posted.

On 850 if its Motronic M4.4 yes it has both Lambda Voltages and Fuel Trims but M4.3 not with App sadly due how it talks.
I believe I have the Motronic 4.3. How do I see O2 sensor numbers?
I think this ECM has been touched best by rkam as this falls under older diagnostic protocols.

But if you are in old ways are best and insist manual labour.. and you are radio amateur who knows morse code.. you are in luck!


You need transfer ECM into DTM 4 mode by shorting Pin with button # 3 in OBD port to GND 4 times. (this is by other manual DTM 3 so 3 times so Volvo is not sure how document this)
Now communication is at rate of x10 so you need be quick reading angrily flashing led light (OBD Port Pin #3 is + and use GND Pin # 4 or 7) and input commands with button you used in previous step.

Next you need know command but if it would be same as Fenix 5.2 then in theory you need quickly input value 53 in decimal so press button exactly that amount in a second!

The now you should get back 8 bytes of data which in theory is what you looking for the value.


..or get Volvo VST handheld device i am sorry.
I appreciate the help anyway. Just the other day your app helped to clear a transmission code that would not respond to conventional obd2 scanners.
Scarlett: 1996 850 Turbo Wagon in Reagent Red Pearl ~210K mi
Norman: 2012 F150 XLT Crew Cab in Oxford White ~110K mi
Ember: 2005 XC90 2.5T FWD in Ruby Red Metallic ~83K mi *Newest addition to the fleet*
Ruby: 1997 850 Turbo Wagon in Reagent Red Pearl - parts car
Rose: 2020 Ram 1500 in Delmonico Red Pearl - SWMBO's Vehicle

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