bad o2 sensor
#1
08-01-2007, 01:04 AM
bad o2 sensor
I have a 1997 volvo 850 glt wagon. Awhile agothe check engine light came on so I took it to a shop to find out what was wrong with the car. Theytold methat the o2 sensor was bad so I had it replaced but then the light came on again a week later so I took the car back and it turned out that the o2 sensor was bad again and they replaced it under warranty. A few weeks later the light came on again andhad to replacethe sensoragain because it went out again. The mechanic I took it to told me that the only thing that he can think of that is causig this to happen is that the turbo is going bad and leaking into the ehaust which iscausing the o2 sensor to go out. The turbo seems to work just fine and there isnt oil inside of it. Would someone please help me out!!
#2
08-01-2007, 02:50 AM
RE: bad O2 sensor
Hello Gabe1827,
O2 sensors on Volvos are noted for being vulnerable, and it is a common problems with miles & age. However, one should not fail asprematurely & oftenas you have described, and I would like to know if the mechanic you took your car to has been installing OEM Bosch sensors that are specific to the '97 850 Turbo. There should be 2 O2 sensors on turbo 850s; front & rear.
>The mechanic I took it to told me that the only thing that he can think of that is causing this to happen is that the turbo is going bad and leaking into the exhaust which iscausing the O2 sensor to go out.
Negative. A turbocharger is driven by the exhaust gas (turbine) and whether the turbocharger is bad or not, the exhaust gas still goes out the tail pipe (unless the turbine is severely deformed or the bearings have burned out, in which case a back-pressure would build up but this should not harm the O2 sensor). And as long as your turbo is functioning fine, it has nothing to do with the problem.
Is the mechanic you took your car to a fully-certified ASE Master Technician? And does he work on Volvos often? If so, you may give him another chance, but neither qualification applies, I wouldgo to a dealer (make sure not to get taken, as some dealers have tendency to sell you hundreds of $$$ of unnecessary parts & services) or an independent shop that specialises in Swedish/European makes.
If you could give us some of the info I suggested, we could better help you.
JPN
O2 sensors on Volvos are noted for being vulnerable, and it is a common problems with miles & age. However, one should not fail asprematurely & oftenas you have described, and I would like to know if the mechanic you took your car to has been installing OEM Bosch sensors that are specific to the '97 850 Turbo. There should be 2 O2 sensors on turbo 850s; front & rear.
>The mechanic I took it to told me that the only thing that he can think of that is causing this to happen is that the turbo is going bad and leaking into the exhaust which iscausing the O2 sensor to go out.
Negative. A turbocharger is driven by the exhaust gas (turbine) and whether the turbocharger is bad or not, the exhaust gas still goes out the tail pipe (unless the turbine is severely deformed or the bearings have burned out, in which case a back-pressure would build up but this should not harm the O2 sensor). And as long as your turbo is functioning fine, it has nothing to do with the problem.
Is the mechanic you took your car to a fully-certified ASE Master Technician? And does he work on Volvos often? If so, you may give him another chance, but neither qualification applies, I wouldgo to a dealer (make sure not to get taken, as some dealers have tendency to sell you hundreds of $$$ of unnecessary parts & services) or an independent shop that specialises in Swedish/European makes.
If you could give us some of the info I suggested, we could better help you.
JPN
#3
08-01-2007, 10:30 AM
RE: bad O2 sensor
The first two times the o2 sensor went out we had taken it to a volvo dealer but then I took it to another shop because the dealer said that they would only replace it once. The shop that it was last replaced at was the place that the mechanic told me the turbo was going bad. Then after replacing it a third time it failed after a week and I have just been driving as is because i dont want to replace it again when the sensor is not the problem. I called the volvo dealer and asked if they knew anything but I dont think the guy I talked to sounded like he didnt know what he was talking about but he said that a failing catalitic converter could be causing the sensors to fail. I hope the clarifies things a little more.
#4
08-01-2007, 07:21 PM
#6
08-02-2007, 03:05 AM
RE: bad O2 sensor
Hi Gabe,
I would ask the shop this question first:
Q: Did you guys replace the O2 sensors with the OEM brand?
If they say yes, the next question:
Q: What was the brand called?
If they couldn't tell you instantaneously that the brand was Bosch, I would leave the shop for good.
Also, to be sure that the O2 sensor(s) is actually triggering the CEL, see if you can visit a local AutoZone or any auto parts store that provides free OBD-II diagnostic service. Generally peaking, the code reader that they use at AutoZone is of Actron (CP9175) and this scanner can read both the code & give you a brief description of the fault.
>but he said that a failing catalytic converter could be causing the sensors to fail
If the cat was actually bad, you would have noticed rotten egg kind of odor from the tail pipe, and the only sensor that would be affected by a faulty cat is the rear O2 sensor.
I hope this gives you some ideas.
JPN
I would ask the shop this question first:
Q: Did you guys replace the O2 sensors with the OEM brand?
If they say yes, the next question:
Q: What was the brand called?
If they couldn't tell you instantaneously that the brand was Bosch, I would leave the shop for good.
Also, to be sure that the O2 sensor(s) is actually triggering the CEL, see if you can visit a local AutoZone or any auto parts store that provides free OBD-II diagnostic service. Generally peaking, the code reader that they use at AutoZone is of Actron (CP9175) and this scanner can read both the code & give you a brief description of the fault.
>but he said that a failing catalytic converter could be causing the sensors to fail
If the cat was actually bad, you would have noticed rotten egg kind of odor from the tail pipe, and the only sensor that would be affected by a faulty cat is the rear O2 sensor.
I hope this gives you some ideas.
JPN
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