O2 Voltage

[Bill]

I have a 01 Forester and the CEL has been coming on (P0420 - "Catalyst
system inefficient for Bank 1"). I posted earlier to this group and it
was suggested that it was the front o2 sensor. I'm finally getting
around to addressing it. I had a friend use his OBD computer and read
the sensor voltages. They were around 5V and I believe the typical
value is suppose to be 0.1 to 0.8 V.

My friend suggested to cross check the voltages with a multimeter. His
suggestion was to use a sewing needle taped to the multimeter probe and
stick it through the insulation. I was wondering if there were any
other suggestions out there?

Thanks,
Bill

 

[nobody >]

I have a 01 Forester and the CEL has been coming on (P0420 - "Catalyst
system inefficient for Bank 1"). I posted earlier to this group and it
was suggested that it was the front o2 sensor. I'm finally getting
around to addressing it. I had a friend use his OBD computer and read
the sensor voltages. They were around 5V and I believe the typical
value is suppose to be 0.1 to 0.8 V.

My friend suggested to cross check the voltages with a multimeter. His
suggestion was to use a sewing needle taped to the multimeter probe and
stick it through the insulation. I was wondering if there were any
other suggestions out there?

Thanks,
Bill

The "sewing needle taped to the probe" trick does work but can be kinda
tricky with just tape. Wrap the tip and needle together with multiple
turns of solid wire (18 ga works well) and then tape over that. I've
done that when I didn't have the fancy factory-made needle-tip probes
available.

 

[Nick Lamendola]

Hi Bill,
My '99 Outback was throwing the same code, it would go away for a while and
then come back. I finally replaced the front O2 sensor and it hasn't come
back since. I had 122k miles on it at the time. I didn't bother checking the
voltage. I was so happy when the O2 sensor unthreaded very easily from the
exhaust system. I made sure it was hot before I attempted removing it, but
it came out a lot easier than I thought it would, I didn't have a the right
socket but I was able to get at it with a smaller crescent wrench. Good luck
-Nick

 

[alf]

Hi Bill,
My '99 Outback was throwing the same code, it would go away for a while and
then come back. I finally replaced the front O2 sensor and it hasn't come
back since. I had 122k miles on it at the time. I didn't bother checking the
voltage. I was so happy when the O2 sensor unthreaded very easily from the
exhaust system. I made sure it was hot before I attempted removing it, but
it came out a lot easier than I thought it would, I didn't have a the right
socket but I was able to get at it with a smaller crescent wrench. Good luck
-Nick

did you use OEM O2 sensor or e.g. Bosh?

 

[Nick Lamendola]

I bought it at the local Parts ++ auto parts store, it wasn't OEM, can't
remember for sure but it might have been Bosch. It had the idetical 3 wire
connector, and a little packet of copper anti seize compound for the
threads. Cost was $84.

 

[Nick Lamendola]

The replacement O2 sensor was made by Denso.
-NL

did you use OEM O2 sensor or e.g. Bosh?

 

[alf]

The replacement O2 sensor was made by Denso.
-NL

thx a lot.

 

[Bill]

NL-

Thanks for the reply. Nice to know that it's not difficult to replace.

Bill