Janko

Ok, so, I'm suddenly getting very poor gas mileage on my 98 Jeep Cherokee. Been told that it's most likely my o2 sensor, but since there's 2 of those, which one should I change?

PatHenry

Both!

If you're tight on money and time, the one that most impacts fuel efficiency is the one before the catalytic converter. In other words, in the exhaust between the engine and cat. The one after the cat is more for emissions/cat function.

Use only NTK or Mopar (which is a repackaged NTK) for the brand. This is what the experts recommend - Jeeps are picky about the O2, so save yourself the headache by getting the right brand the first time.

BlueRidgeMark

The one after the cat only lives to tell the ECM when your cat is tired, so it can light the idiot light. It does not affect the engine running.

Vacuum leaks can also trash fuel economy. Check by spraying a flammable fluid (like WD-40) in areas that may leak. If there is a leak, the fluid will be pulled in add the RPMs will increase.

Janko

Thank you both, PatHenry, and BlueRidgeMark, on your info. I'm a female, but I'm trying to do majority of trouble-shootings and repairs myself. That's why I have to ask all these questions, since I am no mechanic by any means. LOL. But, I can handle simple repairs, and I appreciate all the input provided on this site. Thank you again.

PatHenry

Anytime!

There's nothing in ones gender that gives an innate ability to understand automotive systems or repair them. There are plenty of gals that are a lot handier with a wrench than most guys - so don't ever hold yourself back because society tells you otherwise. Keep up the good work and don't ever feel anything but welcome in this forum.

Janko

Awesome !!! Thank you again. I will be back here for sure, since ya know, a 20 yr old jeep has a lot of questions. LOL.

cpttuna

Do you have an 02 sensor wrench?

Janko

O2 sensor wrench? I've got all kinds of wrenches, but I didn't know you needed one specifically designed for O2 sensors. I even watched YouTube and the guy was using just a regular, adjustable wrench to change his O2 sensor. Is there something I should know? Or since I am a newbie here, this is the way to be welcomed. LOL.

Rambler65

An O2 sensor wrench or socket is designed to give more grip than an adjustable or open-end wrench. Those sensors can be a real bear to get loose!

Janko

Oh, man, OK. Thank you for that info. I had no idea. I've never seen this type of wrench before, but then again, I've never needed to change the O2 sensor before either. You guys are awesome. I really appreciate it. Oh, BTW, does anyone live in Los Angeles? There's another problem I have with my jeep, but so far, no mechanics can figure the problem, and I cannot explain it, cuz it's about a particular type of noise coming from the front end, and it comes and goes. If anybody is here in LA, please, let me know. Thank you in advance.

kgm

My O2 sensor came out really easy once I hit the pipe it was threaded in to with a blowtorch for a minute

Janko

Did you use a regular wrench, or the kind that was posted with a picture earlier?

SirCyber

I thought the O2 wrench had a split to fit over the wires, and give you that box end feel

RocketMouse

X2.... I've been wrenching on vehicles since I was old enough to hold one... I got lucky in that respect....but I completely agree with your statement. I have both men and women friends that can hold their own with a wrench.
Basically anyone willing to take the time and effort to learn can become really good at it.

RocketMouse

Welcome to the family.... and if you haven't already..... you'll learn that Jeeps can have their bouts of being "needy children" every so often. Just the way they are. So getting comfortable with working on them yourself and making peace with the fact that you WILL be working on them will make things quite a bit easier.
The good part about it is there are so many companies still making most of the parts our XJ's need because there are so many still on the road and still so popular, at least the cost of the parts are more reasonable than many other vehicles.