jfryjfry Reader
9/25/16 11:43 p.m.

More of a psa, 2 years ago I replaced the o2 sensors on my e36 m3 to help pass smog. Shortly thereafter I failed smog.


So I ran a can of sea foam through the motor via a vacuum line and the exhaust never seemed to clear up. I figured I had killed my cats. So I grabbed a set of cats from a buddy who just swapped an ls into his m3. I used my awesome cordless impact to bust off my exhaust and after installing his, I had a check engine light come on.

Crap again.

codes said I lost both o2 sensors which I had left installed in the car for the cat swap and which are pretty close to the joints I took apart.
That's when I learned that the hammering action of the impact wreaks havoc on delicate o2 sensors.

So I shelled out another wad of cash and bought my 3rd and 4th brand new bosch o2 sensor in as many weeks.

Moral of the story: gently remove your o2 sensors before beating away on the exhaust - especially with an impact.

dean1484 MegaDork
11/10/16 4:22 p.m.

Good to know!!!

11/10/16 5:21 p.m.

I've run across that on a customer's car. Used an air chisel on a broken stud on the downpipe. The MIL was on for the O2 sensor as soon as I started it up.

BrokenYugo UltimaDork
11/10/16 6:33 p.m.

Yup, don't drop them either. They also tend to only last about 100k before they start reading lean and costing you considerably more in fuel than a new sensor. Amazingly delicate things considering they live on an exhaust downpipe or sometimes right at the end of the manifold.

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