96 850 turbo O2 sensor
#1
05-14-2007, 03:41 PM
96 850 turbo O2 sensor
Hi guys.
I have a problem. With my ODBII reader I get this readin from the sensor " closed loop O2 sensor fault"
I have changed both O2 sensore with Bosch OEM replacements but I still get the same reading. The car does NOT throw a trouble code
at all and the CEL is off.
Has nyone else seen this problem. Is it a problem at all? Why would it keep saying sensor fault after I change them. When the ar starts it is in
open loop mode and then after a few minutes it goes to closed loop sensor fault.
Thanks
-greg
I have a problem. With my ODBII reader I get this readin from the sensor " closed loop O2 sensor fault"
I have changed both O2 sensore with Bosch OEM replacements but I still get the same reading. The car does NOT throw a trouble code
at all and the CEL is off.
Has nyone else seen this problem. Is it a problem at all? Why would it keep saying sensor fault after I change them. When the ar starts it is in
open loop mode and then after a few minutes it goes to closed loop sensor fault.
Thanks
-greg
#3
05-14-2007, 10:52 PM
RE: 96 850 turbo O2 sensor
Hi Greg,
I can only suggest that you check for vacuum leak, mostly from "elbows", which are rubber/plastic tubings mainly located under the throttle cover (some are located in front of the radiator, like the one for EGR valve). BTW, is your 850 turbo or NA?
Other members may be able to give you another perspective.
JPN
I can only suggest that you check for vacuum leak, mostly from "elbows", which are rubber/plastic tubings mainly located under the throttle cover (some are located in front of the radiator, like the one for EGR valve). BTW, is your 850 turbo or NA?
Other members may be able to give you another perspective.
JPN
#4
05-15-2007, 01:16 AM
RE: 96 850 turbo O2 sensor
Well here is my problem.
These are the numbers before I changed both O2 sensors.
15Mph HC Max 52 Measured 16 CO% Max .49 Measured .24 NOx Max 424 Measured 941
25 Mph HC Max 36 Measured 13 CO% Max .46 Measured .20 NOx Max 711 Measured 925
After I changed my O2 sensors these were my smog test numbers
15Mph HC Max 52 Measured 8 CO% Max .49 Measured .02 NOx Max 424 Measured 436
25 Mph HC Max 36 Measured 4 CO% Max .46 Measured .03 NOx Max 711 Measured 137
As you can see in bold I am 12 ppm over the allowed amount. The car is a turbo and everything is working within spec.
I have no idea what to do next to pass. I will check my vacuum lines like you say to make sure but I doubt that is a problem.
The car is in good shape.
Ta nks
These are the numbers before I changed both O2 sensors.
15Mph HC Max 52 Measured 16 CO% Max .49 Measured .24 NOx Max 424 Measured 941
25 Mph HC Max 36 Measured 13 CO% Max .46 Measured .20 NOx Max 711 Measured 925
After I changed my O2 sensors these were my smog test numbers
15Mph HC Max 52 Measured 8 CO% Max .49 Measured .02 NOx Max 424 Measured 436
25 Mph HC Max 36 Measured 4 CO% Max .46 Measured .03 NOx Max 711 Measured 137
As you can see in bold I am 12 ppm over the allowed amount. The car is a turbo and everything is working within spec.
I have no idea what to do next to pass. I will check my vacuum lines like you say to make sure but I doubt that is a problem.
The car is in good shape.
Ta nks
#5
05-15-2007, 01:34 AM
RE: 96 850 turbo O2 sensor
Hi Greg,
I remember that one of the forum members has had similar problem, and he has had almost everything done and still couldn't manage to get it right.
If it's the NOx number that's the only thing keeping you from passing the emissions test, I can only assume that the EGR system needs servicing. You could either clean it or replace it with a new unit. Also, make sure that the connection to EGR are good, as there are many people who intentionally disable EGR for whatever the reason.
The O2 sensors seem to be working fine, judging from the readout. I am not certain why your scanner keeps getting the signals.
Other than the vacuum connections & EGR system, you could try dumping a larger bottle of Techron fuel system cleaner, cleaning the air filter with a vacuum cleaner or replace it (though it may not change the NOx reading), etc... When was the last time it had a good tune up (plug, plug wires, distributor cap & rotor)?
Should you decide to attack the EGR, here's a good parts source:
http://www.fcpgroton.com/volvo850fuelsystem.htm
Wait till other members can give you other possibilities.
JPN
I remember that one of the forum members has had similar problem, and he has had almost everything done and still couldn't manage to get it right.
If it's the NOx number that's the only thing keeping you from passing the emissions test, I can only assume that the EGR system needs servicing. You could either clean it or replace it with a new unit. Also, make sure that the connection to EGR are good, as there are many people who intentionally disable EGR for whatever the reason.
The O2 sensors seem to be working fine, judging from the readout. I am not certain why your scanner keeps getting the signals.
Other than the vacuum connections & EGR system, you could try dumping a larger bottle of Techron fuel system cleaner, cleaning the air filter with a vacuum cleaner or replace it (though it may not change the NOx reading), etc... When was the last time it had a good tune up (plug, plug wires, distributor cap & rotor)?
Should you decide to attack the EGR, here's a good parts source:
http://www.fcpgroton.com/volvo850fuelsystem.htm
Wait till other members can give you other possibilities.
JPN
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