Oxygen Sensor!!!

I have a 2000 Cherokee with a 6 cylinder. I went to AutoZone to find out why the check engine light is on. The codes read that the oxygen sensors are bad. How hard is it to replace this part? Is it worth taking it somewhere to have it done? What brand oxygen sensor do you recommend I get and from where? Is there a special tool required to do this? Are there more than one oxygen sensor or is it one piece?

2000XJ - did it say which HEGO sensor you lost? Or are you planning to "shotgun" it and change them all?

The later the vehicle, the more HEGO sensors you'll have - I'm inclined to think that there are at least two, and possibly four, sensors on the 2000 (but I'm not sure.) They're easy to spot - look for something like an oversize spark plug sticking out of the exhuast plumbing, and be sure to look under the vehicle for one or two after the catalytic converter.

You can buy the parts in the aftermarket (some prefer Bosch, I prefer ACDelco - both will work neatly,) and change them yourself. Make sure you get a HEGO sensor socket (it's a 7/8" extra deep with a notch milled in the side to clear the wiring, expect to pay $15-20 for it,) and all necessary sensors, AND a tube or jar of Anti-Seize.

Warm up your engine and plumbing somewhat (it's easier to remove them when warm) and kill the engine. Remove & replace the sensors, making sure you apply Anti-Seize to the sensor threads ONLY. Most sensors will come with Anti-Seize on the threads already, but I like to add some more. Make sure you DO NOT get any of the paste on the sensor tip proper - that's the cage sticking out past the threads! If you do that, you'll contaminate the sensor and end up AT LEAST taking it back out and cleaning it!

Once the sensors are replaced, disconnect the negative battery lead for 1-5 minutes (to "reset" the PCM) and take your vehicle for a couple short drives to "relearn" with the new sensors. You should be fine after that.

Is it worth doing it yourself? I think so - the sensor socket will cost far less than the labour, the sensors themselves will cost less without shop markup, and you'll know what was done afterwards - plus, you'll be able to spot anything else amiss. I don't farm out much work on my vehicles - just tyre changes (I don't have a tyre changer and a tyre balancer) and smog checks (since the "Great State of California" won't let me. I still do all smog-related repairs myself.)

5-90

Changing the oxygen sensor is stupid easy. It amazes me how many people go to a shop for that and air filters (something I think is the easiest maintenance item). Its just an electrical connector and a threaded plug inserted into the exhaust downpipe they even come with anti-sieze pre-applied. All I use is a box end wrench to do it but you can also buy a socket that fits the sensor (all pretty much same size) and this socket has a slit for the cables. Bosch and NTK (NGK) are the big manufacturers, Bosch (at NAPA) is they pioneered the use of O2 sensors. When you have engine check codes, you should first try to determine if its really sensor failure or if another problem like a bad connection or uncontrolled a/f ratio (vaccuum leak for example) is mis-interpreted for a bad O2 sensor by the ECU.
The upstream O2 sensor(s) are involved with a/f ratio control, the downstream one simply throws a code if the cat needs replacement. There usually is little need to replace the downstream one (if you have one) unless it is causing codes to be thrown.

Not real sure about the 2000 model. Usually there are only two oxygen sensors (a.k.a. O2 sensors), both mounted in the exhaust pipe--one near where the exhaust pipe passes the back of the oil pan, one on the back end of the catalytic converter, before the muffler. Some 2000-2001 models in California have 4 O2 sensors, I guess, two in the exhaust manifold, plus the other two I have already mentioned.

They do NOT require any special tools to remove & replace them. Usually just a 22mm box end wrench. But you might want to check with someone who drives a 2000. Mine is a '96.

Thank you!

I will do it myself. I'll let you know how it turns out.

so no one knows for sure how many are on there? 4 o2 sensors or 2? I dont have the car here at work so I cant check. I would like to call Kragan though to get an idea of how many they are. Im sure they guys there are retarded and dont know how many there are even with their computers.

Well, if I owned an XJ made that late, I'd know... :laugh3:

Seriously tho, I seem to recall that the later OBD-II XJ's had the exhaust divied into two "banks" - 1-3 and 4-6 - so it seems to me there will be at least three. I'd not call Kragen's to find out - I worked there for three and a half years, and most of those people were droids then. They have only declined since...

It would probably be more worthwhile to see if anyone's profile lists a 99/00/01XJ, and PM them to ask. While you're digging, you might want to find Tech Authority and get an FSM for your XJ - it would bring the cost for this job to be "on par" with what you'd spend at a shop (typical FSM cost ~$90) but that book will save you thou$and$ later on labour and diagnostics - plus the incalculable value of actually understanding your vehicle later...

5-90

Are you talking about getting one of these?




Is this one the best IYO?

fdsa487 said:

Is this one the best IYO?

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Not exactly - he's talking about the FSM (Factory Service Manual) as used in Jeep dealerships. Whole other beast altogether. Some Googling may get you pointed in the right direction.

FWIW, neither the Haynes or Chilton's manuals are any better than the other. Both get things wrong, underdescribe procedures, and have an annoying tendency to say 'take it to the dealer' at the wrong point. Having said that, they're both fairly good guidelines on doing stuff you may be unfamiliar with; just be prepared to adapt & improvise as necessary. Check both, see which one you like better, and go with it. I say this from my experience with the Haynes; a friend of mine has the Chilton's so my opinion is derived largely from occasionally using his manual. They're certainly better than nothing, though.

Getting back to the 'how many oxygen sensors does it have' question: if it's a California-model 2000 or 2001, it should have four (IIRC); this jives with what my 2001 Sport had. If it's a 49-State model, you'll probably only have two, which is what's on my current 2000 Limited. Unfortunately, we can't answer this question for you since we have no idea if yours is a California or 49-State model.

Checking for the number of sensors is really easy. Start at the exhaust manifold and follow it back to the muffler. At various points along its length you'll see what look kind of like spark plugs (complete with wires running from their tops) screwed into the pipe. Those are your oxygen sensors, and they just unplug and screw out/in. Note that the sensors in each location will probably be different - check the numbers on the sensor casings to confirm this.

If the Jeep is under 80,000 miles, they may be covered by law under warranty as defective emissions parts; check with a dealer on this, but you may be able to get them changed for free. If over 80,000 miles and you have no idea what state they're in, I'd almost recommend replacing the whole lot at once just so you know it's done. Replacing just the one that's acting up won't hurt anything, though.

casm said:

Not exactly - he's talking about the FSM (Factory Service Manual) as used in Jeep dealerships. Whole other beast altogether. Some Googling may get you pointed in the right direction.

FWIW, neither the Haynes or Chilton's manuals are any better than the other. Both get things wrong, underdescribe procedures, and have an annoying tendency to say 'take it to the dealer' at the wrong point. Having said that, they're both fairly good guidelines on doing stuff you may be unfamiliar with; just be prepared to adapt & improvise as necessary. Check both, see which one you like better, and go with it. I say this from my experience with the Haynes; a friend of mine has the Chilton's so my opinion is derived largely from occasionally using his manual. They're certainly better than nothing, though.

Getting back to the 'how many oxygen sensors does it have' question: if it's a California-model 2000 or 2001, it should have four (IIRC); this jives with what my 2001 Sport had. If it's a 49-state model, you'll probably only have two, which is what's on my current 2000 Limited.

Checking for the number of sensors is really easy. Start at the exhaust manifold and follow it back to the muffler. At various points along its length you'll see what look kind of like spark plugs (complete with wires running from their tops) screwed into the pipe. Those are your oxygen sensors, and they just unplug and screw out/in. Note that the sensors in each location will probably be different - check the numbers on the sensor casings to confirm this.

If the Jeep is under 80,000 miles, they may be covered by law under warranty as defective emissions parts; check with a dealer on this, but you may be able to get them changed for free. If over 80,000 miles and you have no idea what state they're in, I'd almost recommend replacing the whole lot at once just so you know it's done. Replacing just the one that's acting up won't hurt anything, though.

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It is a California Model 2000. It does have under 80K miles. If i called the dealdership would they know of should I go down there?

fdsa487 said:

It is a California Model 2000. It does have under 80K miles. If i called the dealdership would they know of should I go down there?

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I'd call Jeep (not the dealer, the DCX customer help line) first and check that the oxygen sensors are covered.

Once you have that information (or even if Jeep says 'no'), call (or go down to) the dealer. Explain that you've already talked to Jeep, and outline what you need to have done.

If the warranty's valid, chances are the dealer will want to keep it to replace the sensors themselves. If this is the case, fine, do it, the labour should be free as well - but verify that this is the case beforehand.

Otherwise, sorry, you'll have to stump up for new sensors.

I would strongly advise doing the sensors yourself. It's an easy job and will get you more familiar with the vehicle. Not to mention what shop labour rates cost - I'd had my first XJ about three weeks when I thought I'd blown the transmission in a water crossing. Made the mistake of taking it to the dealer; $270 later, I had a new TPS. Not only did I panic and misdiagnose the problem, I spent the thick end of three hundred bucks replacing a $40 part that can be swapped out in well under half an hour. Moral of the story: being your own mechanic beats being taken by them.

casm said:

I'd call Jeep (not the dealer, the DCX customer help line) first and check that the oxygen sensors are covered.

Once you have that information (or even if Jeep says 'no'), call (or go down to) the dealer. Explain that you've already talked to Jeep, and outline what you need to have done.

If the warranty's valid, chances are the dealer will want to keep it to replace the sensors themselves. If this is the case, fine, do it, the labour should be free as well - but verify that this is the case beforehand.

Otherwise, sorry, you'll have to stump up for new sensors.

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What is the DCX customer help line and how do I get ahold of them?

fdsa487 said:

What is the DCX customer help line and how do I get ahold of them?

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DCX = Daimler/Chrysler. The number should be Googleable.

casm said:

DCX = Daimler/Chrysler. The number should be Googleable.

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Sorry to bug you so much but what would you say to them?

fdsa487 said:

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What happened to these things? They use to weigh like bricks. Now they not much heavier than my newspaper...

They got cheap. The FSM is your best bet, with Chilton's being a poor second. I use Haynes manuals to prop up the odd legs on workbenches now...

Where, oh where, did Clymer's manuals go?

5-90

I called Crysler and spoke with someone. They took the last 9 of my VIN and put me on hold. When she came back to the phone she said that only the catilitic converter is covered for 80K miles. FYI

fdsa487 said:

I called Crysler and spoke with someone. They took the last 9 of my VIN and put me on hold. When she came back to the phone she said that only the catilitic converter is covered for 80K miles. FYI

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Okay, double-check that with them. California law is more extensive in this regard as a general rule, so it's possible that she either a) wasn't aware of this or b) didn't know you're in California (I'm assuming El Cajon from your profile). Also check it with a dealer, because they may very well be more up on it than DCX is.

casm said:

Okay, double-check that with them. California law is more extensive in this regard as a general rule, so it's possible that she either a) wasn't aware of this or b) didn't know you're in California (I'm assuming El Cajon from your profile). Also check it with a dealer, because they may very well be more up on it than DCX is.

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Will do.
Thanks for the info. And you thinking about it more I think that there are 4 sensors under there.