I'm trying to verify the location of "Bank 2 sensor 1".

Driver's side, upstream of catalytic converter?

Look down at the rear of the engine. OEM O2 sensors often have a blue cable. If yours does find it and follow it. IIRC, the bank 1 is easier to see so you might want to identify that one first.

__________________
Good luck.






1998 E320 Wagon

You're right about the location.

Pop off the engine cover and follow the exhaust manifold and you'll see it. It threads in from the top.

If you have one coding, you may as well replace both of the front ones.

It's easier if you buy a set of "wobble" extensions, and quicker if you buy the direct-fit ones.

Good luck.

Ha! I got lucky... Found it loose.

That also explains the faint 'tick' I've been hearing.

Sheesh. I never have that kind of luck!

Congrats!

Not so fast...

I've been driving this car for two weeks, the wife drives it last week and comes home and says the CEL is on. I reset it and drove it for a week never illuminating the CEL. She drives it last sat and it reappears. WTH???

Yesterday I find the loose "Bank 2 sensor 1", tighten it and reset the light. I put about 25 miles on the car afterwards. It ran fine as always and no CEL. I'm thinking it's fixed.

The wife uses it to take our 5 year old daughter to dance class around 5 pm. Calls me and tells me the CEL is on again. CRAP!

At least I am confident I can get the O2 sensor out.

Looking at the O2 live output...

Bank 1 sensor 1... 0.100- 0.700 varies a lot.
Bank 2 sensor 1... 0.475 little change, seems to stay there.
Bank 1 sensor 2... 0.685 varies but, not much.
Bank 2 sensor 2... 0.105 also varies but, not much.

What puzzles me is the difference in output from all four. B1S1 seems to have a good swing with throttle change while the others not so much. Hmm...

Can someone give me some insight as to what I should be seeing?

The car runs fine, has plenty of power and returns 26-28 mpg average.

sounds like lazy sensors - in my car the pre cat ones create a nice wave pattern, while the post cat ones stay stable.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

It's tempting to replace all four.

Anyone had luck with using the $70 Bosch universal O2 sensors? Otherwise, I'm looking at $200+ per sensor.

Do all O2 sensors have the same output reference voltage? In other words, as the temp, O2 level changes do they all track at the same output voltage? If so, I would expect the less expensive universal sensors to communicate the proper signal for fuel management as well as the original part for a fraction of the cost.

Two points about the so-called "universal" sensors.

First, so long as you get the ones specified for your car, you're fine. They are not really "universal," but rather you only replace the sensor and re-use your harness connector, so you have to splice it together. Not at all difficult.

Second, look them up on Bosch's USA parts finder, I would definitely avoid using vendor catalogs. There are lots of variations.

Once you get your part number(s), search for them on various parts sites, including Amazon. That's the place I found them for the cheapest, and sometimes I see the direct fit ones for not much more, so that may work for you as well.

Also, the rear ones monitor the cats; as I understand it only the front ones are used to regulate fuel flow. So you might just replace the front ones and leave the rear ones until they actually fail.

Good luck.