Welding of o2 sensor into manifold!


I recently took my 2000 Honda Civic LX in for servicing because the “Check Engine” Light came on. It turned out to be the o2 sensor, and about two hundred dollars later the problem was fixed. I was pretty happy; however, less then one month later the “Check Engine” light was on again so I took the car to the dealership. The dealership told me the problem was with the o2 sensor …and that the o2 was welded into the manifold/catalytic converter (all one piece in Civic). OH NO! Over $1,000 later, the problem was fixed.

Question: Is it a common practice to weld the o2 sensor? Did they strip the threads? Should I take them to small claims court if I don’t receive satisfaction?


I’m not sure I’m understanding exactly what happened. Did you take it to an indy shop which welded the O2 sensor into the cat, and then the DEALER re-fixed it with a new cat and O2 sensor as a unit? I’m not that up on Hondas, but I can’t see why the factory would weld one into the catalytic converter, unless it was to make the cost of ownership and their profits higher.

How many miles are on this car? What’s the warranty on emissions specific items on a Honda? Aren’t they all 100K?


As usual, there’s a bit missing.
You took your car “in for servicing” because the CEL was on.
So, who did you take the car to for this servicing?

It sounds like you went to an independent shop, developed a problem with the repair they did, and then discovered at the dealer the repair may have been botched.

An O2 sensor should never be welded, brazed, soldered, or stapled into place. If this O2 was welded then the only reason I can think of that someone would do something so stupid would be if they stripped the exhaust pipe bung hole threads out during removal of the old one and figured that tack welding a few spots was the quickest easiest way to get the car out the door.


When they said welded they probably meant that it was corroded in place and they couldn’t get it out.

If they needed to replace the O2 sensor and it was welded/frozen why not just drill another hole close to the old one, weld in an o2 sensor bung, and then screw a new one into the bung and abandon the old sensor.


Sometimes, people use the term “welded” to describe something that is just really stuck in place. Was there an actual weld bead holding the sensor in? If so, you should speak with the shop that did the work to try and recover some of the money you spent to repair it. If it were me, I’d be happy with 1/2 the cost of the repair because it may be no fault of theirs that the thing was so stuck in the first place that they stripped the threads taking it out. However, they should have fessed up at that time and explained your options.


Wow, my post never showed up!

Anyway, what I said was, there is rarely enough room to do that kind of work with the manifold in place. The solution is to remove the manifold, grind off the damaged bung and weld a new one in its place.


I am curious as to what 02 sensor was replaced by the first shop. If they changed the post cat 02 then they have no fault regarding the pre cat 02 sensor.