Hey everybody, I need your help in verifying the right Oxygen sensor I need. I have a 2003 Liberty with the 3.7L V6. I need the Oxygen sensor that sticks up out of the exhaust pipe on the passenger's side underneath the Jeep near the oil pan. I believe this is the "right side downstream" Oxygen sensor. Am I correct? Thanks.

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2016 Jeep Wrangler Unlimited

yes thats the one
number 2/2

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MUDD'S MOTORSPORT'S We do IFS lift installs ,
03 OVERLAND EDITION /Kilby-Skidrow-Mopar-4XGuard skids/ 2.5 inch TOTAL CONTROL JBA coilovers -JBA Arms/MOABS-31 FALKEN WILDPEAK AT3W / 4.10's etc, 04 Kilimanjaro Edition loaded, plus 05 KJ limited

Thank you much for the help Tom.

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2016 Jeep Wrangler Unlimited

Next question: how much of a PITA is it to replace? It looks relatively accessible, but I'm a little nervous about messing up the electrical connection. Any tips and tricks are greatly appreciated.

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2016 Jeep Wrangler Unlimited

usually you use the same techniques as a sparkplug. There is an inexpensive socket available at any parts store that has a long slit down the side for the wire to poke out.
There should be a disconnect up the wire aways
Use a little anti-sieze on the threads.
Any fumes or molecules of mist of any silicone product will instantly react/bond with and destroy the chemical compound that senses the oxygen. Kinda like carbon monoxide and your red blood cells.

http://www.youtube.com/watch?v=JXRJpCie ... re=related

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2012 Liberty Latitude 4x4,3.7L,42RLE,MP1522,D30M/8.25"@3.73,215/85R-16 LTX A/T2,Bright White
1974 CJ5,258,T14a,D20,D30/D44@3.73,TransAm Red

Ok. I finally was able to replace the passenger side downstream oxygen sensor. However, the symptoms that caused me to replace it in the first place are still occurring.

The old sensor would smoke and make one of the most acrid smells ever. The best I can describe the smell would be similar to school bus exhaust. It used to be that I would have to turn off any A/C or heat when I came to a stop so that the smell would not come into the cabin, but it recently started seeping in even when I would turn the climate controls off. I never had a CEL or other idiot light turn on, and there have been no other noticeable issues. As I stated, I just replaced the oxygen sensor today. The new one also smokes and smells.

Any ideas?

The guy at the auto parts store thought maybe the catalytic converter was going bad. I looked up some information on symptoms of a failing catalytic converter (rotten egg smell, rattling when hit with a rubber hammer, loss of power, decreased fuel mileage ), but I have not experienced any of these.

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2016 Jeep Wrangler Unlimited

Your valve cover gasket(s) is leaking oil - a common problem with the 3.7 engine.

The gasket leaks at the bottom, rear-most point against the firewall. If you look at the bottom bolt and follow it directly down you can see that a drop (drips) of oil will land directly on the hot catalytic converter instantly vaporizing the oil (that's why you never smell the smoke when the Jeep is cold.) And your cabin intake is at the base of your windshield right above where the smoke originates. Hence, when you come to a stop your HVAC system sucks in the smoke and blows it right in your face. Not pleasant...

The problem may be happening on both sides though not as bad on the driver's side - yet. A set of gaskets from the dealer will run you around $50 or get Fel-Pro gaskets from NAPA or other parts stores. The project can be done at home. The passenger side is tougher because of the coolant reservoir and water pipes for the heater. The A/C lines won't be a problem.

Remove the hoses from the coolant tank, plug them and remove the nuts holding the tank to the firewall and put it aside. Remove the two bolts that hold the oil fill spout in place; disconnect the supply and return lines to the heater core. With the oil spout removed the pipes can be moved out of the way.

Then go about loosening the bolts holding the valve cover in place and pry it out of the way. There are clips on both sides that hold wire harnesses in place; you'll need to pull those clips off the valve cover bolts and move the harnesses out of the way. Take off the gasket and scrape any crud off the head and cover; use the new grommets that come with the gaskets.

Unfortunately you replaced an O2 sensor that was fine. But the good news is your catalytic converters aren't the problem.

Keep us posted!

Bob

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2003 Liberty
- 3.7L V6, NP242 SelecTrac Transfer Case
- OME 927/948's, Bilsteins, JBA Gen 4.5 A-arms, JBA 1/4" top plate, 3-ring clevis, 2 extra rear isos
- Rubicon Moabs
- 4.10's, 265/70-16 Goodyear Duratracs
- 4X Guard Trans Skid, Modded BoulderBars, Mopar Engine, T-Case, Tank Skids, ARB bumper, Smittybilt 9500XRC winch

Bob:

Thanks for the info. It had crossed my mind that maybe something was leaking onto the oxygen sensor. I've noticed oil/sludge on some of the fluid lines and other surfaces under the Jeep near the oxygen sensor. It's mostly concentrated around the oil pan and transmission area. Though, I hadn't ever noticed any oil or other fluids seeming to get on the cat or the oxygen sensor. But it sounds reasonable.

You are right about the smoke and smell not starting until the Jeep has run for a minute. I'll run it again and try to make sure I hadn't just been imagining the smoke coming from the oxygen sensor and try to pin point that it is coming off the cat. In any event, I guess I'll have to live with it for the time being.

James

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2016 Jeep Wrangler Unlimited

You're welcome.

There's nothing to create smoke from the O2 sensors - smoke/exhaust may leak around them if they aren't tight to the cat (though you'd get a CEL if that was the case) so you can pretty much eliminate them as the source of the smoke.

The valve cover gasket may seem a little daunting when you first look at the top of the engine but it is less hassle IMO than the O2 sensors. Once things are moved out of the way they're very accessible.

Once the cold weather gets here the burnt oil smell will become more obnoxious since you'll be running the heater - sometimes at a high fan speed. Nothing like sitting at a light and have that smell hit ya in the face. I didn't change my gaskets till the spring cuz of the cold but I wish I had done it earlier.

Bob

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2003 Liberty
- 3.7L V6, NP242 SelecTrac Transfer Case
- OME 927/948's, Bilsteins, JBA Gen 4.5 A-arms, JBA 1/4" top plate, 3-ring clevis, 2 extra rear isos
- Rubicon Moabs
- 4.10's, 265/70-16 Goodyear Duratracs
- 4X Guard Trans Skid, Modded BoulderBars, Mopar Engine, T-Case, Tank Skids, ARB bumper, Smittybilt 9500XRC winch

I took a look under the jeep and though I couldn't find exactly where the oil leak was coming from, but there definitely is one. It was a quart low, there was oil on the Oxygen sensor electrical connector and wire cover as well as on the block and elsewhere. I guess i'll just have to continue dealing with it and turning off the climate controls as needed for the foreseeable future.

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2016 Jeep Wrangler Unlimited

What are symptoms of a bad O2 sensor? I've had this thing just over a year and it's been nothing but one problem aftert the other. Hell i just had both head gaskets replaced at 47,000 miles(!!!!!!) and it is still running rough. Exteremely noticeable whe I use regular unleaded, but if I use midgrade it always idles smooth. Weird??
Regular high quality gasoline makes my 3.7 shake like i'm in a tank and theres a "whoop whoop whoop whoop"
sound as it rocks back and forth that feels/sounds like a misfire. The elctrical system has been checked and is fine.

I was thinking of changing out the O2 sensors and seeing if this cheap fix could be the problem.. I just have no idea what the heck else to do. Also, its even getting worse gas mileage now that the head gaskets were replaced than it was before they were.

Well, I finally got around to changing the passenger side valve cover gasket. Things went relatively smoothly until I bolted it back up. I went to torque the front bottom stud and it snapped. So, aa it stands, everything is back together with the exception of that one stud. There are no obvious leaks coming from that area nor from the back of the valve cover which was the initial problem. I have my fingers crossed that missing that one stud won't be that big a deal.

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2016 Jeep Wrangler Unlimited

Bob is dead on withe valve cover answer and solution. Same year same problem same solution on mine.----Thanks for the info! You saved me a lot of time and trouble.