Hi - how common are the O2 sensors failing for a Santa Fe. I was checking this forum and others and found that the sensors having failed for quite a large number of vehicles. Mine's still under warranty, so wondering if it's an issue I need to be careful of? Also - where are these sensors, any leads: appreciated.

I would say that O2 sensors are one of the most often replaced sensors, not on any particular car, just in general. On your 4 cylinder Santa Fe, you will have 2 O2 sensors: one in the exhaust manifold itself and one further downstream in the exhaust pipe underneath the vehicle.

Thanks LilBean. Is it feasible to do a DIY change of these sensors? From your desc. of location of these sensors, I am not sure. Is it located INSIDE the manifold and then INSIDE the downstream exhaust pipe?

They screw into each location from the outside of the pipe. The most difficult parts are 1)getting an O2 sensor socket from your local auto parts store, and 2) breaking the sensor loose to remove it as the heat has a tendancy to "weld" in it. It is very difficult to break it loose by hand.

Other than those two things, replacement is pretty straightforward.

You're right, it seems these sensor require a specialized wrench to remove it. Basically, has a cut on one side, very very difficult to find in stores. Tried 3 stores. I think I'll get this done thru dealer only. The welded part is next, as I dunno.

google "02 sensor socket", they are very inexpensive and easily purchased. soak in penetrating oil or something similar for a while and that should help remove them. a tiny bit of anti-seize on the new one will help future removal (a little goes a long ways)

on a V6 there are 4 O2 Sensors... two before the cat and 2 after from what I heard.

O2 sensors might be inexpensive, however they are a real pain to remove. They, due to heat gets "welded" etc. into the manifold and furthermore Hyund requires a special wrench to remove them (slotted on 1 side, very difficult to find after-market). I am coming across some horror stories for those DIY fans where manifold requires to be changed, due to sensor breaking in two, where connected.

The tool (a socket with a slit down the side) you're referring to isn't difficult to find -- try your local Advance Auto Parts or AutoZone (East Coast -- your mass-market parts store may vary by location), they'll even loan it to you for a small deposit. The only problem is that you can't put massive torque on it without bending its wall. Use air tools carefully if you go that way.

As for the sensors self-welding to their sockets, heat made them seize up in the first place, so use heat to free them. The best tool for this is an oxyacelyene torch with a very small welding tip. It'll go a little slower with a plumber's torch (propane or MAPP) and penetrating fluid, but you can get there with some patience.

I second the anti-seize recommendation -- not just for O2 sensors, but also for any steel thread that sinks into aluminum, like spark plugs, surge tank bolts, etc. Buy a bottle rated thermal (up to 1300 F I think) ... it'll last you for years and is useful just about everywhere. Somebody else said that a little goes a long way -- all true.

I'll also tell you that air intake conditions sometimes make O2-related codes pop (particularly P0172-175). Make sure you have no obstructions in your intake system before you take the plunge into O2 sensors. Having to buy one isn't bad ... 4 kinda dings your wallet.

Good luck.

This post has been edited by jtison: Aug 29 2008, 06:08 PM