On my 92 XJ, 143K, runs great, when to replace 02 sensor? I got maint. reqd light at 120K exactly, ran/runs great. But a few months ago, put on 30x9.5 tires, I show approx 15 mpg when I used to get 17-19 and 21 on highway watching speed(70 or under). What is difference in REAL mileage w/ 30x9.5's? Dealer says $102 for 02 sensor, should I replace? Besides that runs and starts great. Thanks, Heinz
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When to replace 02 sensor(s??) 92 4.0 XJ
- Thread starter Heinz
- Start date
- Location
- Terra Firma
The O2 sensor is supposed to be replaced approximately every 80,000 miles. A sudden drop in gas mileage is a good clue that yours is overdue for replacement.
Also...dont forget that your mileage is slightly lower due to the fact that your speedometer may not be calibrated for the 30 inch tires. Maybe its not so much your O2, but your speedo gear...
You should be able to get that O2 sensor at a local parts store for a bunch less than the dealer.
You should be able to get that O2 sensor at a local parts store for a bunch less than the dealer.
kevin s
NAXJA Forum User
- Location
- cincinnati, ohio
$60+ at autozone. Easy to get to and replace. You don't even need the special slotted socket. Just use an open end wrench. Did you have the emissions light reset at the dealer, or just pull the bulb?
Suppposed to come on at 85,000. x2 would equal 170,000. If it was replaced at 85,000, you shouldn't need one yet. If it goes bad, your mileage will drop a little and you will fail smog test. BTDT. Then you will know it's time for a new one.
Suppposed to come on at 85,000. x2 would equal 170,000. If it was replaced at 85,000, you shouldn't need one yet. If it goes bad, your mileage will drop a little and you will fail smog test. BTDT. Then you will know it's time for a new one.
2xtreme
NAXJA Forum User
- Location
- Kayak Pt, WA
The o2 sensor is supposed to be replace at 80K (previously stated also).
You can get one from Napa for $65.
Easy to change, I just used a open ended wrench also.
There is also a electric test for testing the o2 sensor so you could try that if you are suspiciouse (it is in the FSM). When they go out they can cause difficult to track problems with idle and response.
Get the correct spedo gear for you set up with new tires and re-check fuel milage.
Michael
You can get one from Napa for $65.
Easy to change, I just used a open ended wrench also.
There is also a electric test for testing the o2 sensor so you could try that if you are suspiciouse (it is in the FSM). When they go out they can cause difficult to track problems with idle and response.
Get the correct spedo gear for you set up with new tires and re-check fuel milage.
Michael
pancake
NAXJA Forum User
- Location
- Seattle, WA
When you say replace the sensor...do you mean the one BEFORE or AFTER the cat? :anon:
pancake
NAXJA Forum User
- Location
- Seattle, WA
Re: 02 Sensor which one?
Oh, I worded my question poorly.
I was actually asking which to replace.
Heinz said:
Oh, I worded my question poorly.
I was actually asking which to replace.
- Location
- Terra Firma
Two different answers.
Heinz has a '92 -- that only has one O2 sensor.
The two O2 sensors came with OBD-II -- the one after the catalytic converter is basically only to confirm that the converter is converting. The one that provides feedback to the ECU (or PCM) is the first one, the one upstream of the cat.
Heinz has a '92 -- that only has one O2 sensor.
The two O2 sensors came with OBD-II -- the one after the catalytic converter is basically only to confirm that the converter is converting. The one that provides feedback to the ECU (or PCM) is the first one, the one upstream of the cat.
AlanH
NAXJA Forum User
- Location
- Marietta, GA
Before you change your speedo gear, check the accuracy of your current set-up. After I put my 30x9.5 BFG AT's on, I checked the speedo by timing myself between mile markers on the interstate while I was showing 60 MPH. I get exactly 60 seconds per mile, so my stock set-up is actually perfect for the 30 inch tires.
martin
NAXJA Forum User
- Location
- Huntsville, AL
Guys do not use the speedo to verify the odometer. I suggest you go driving on an interstate highway for 50 miles. Record your beginning mileage then drive until 50 and record it again. From this you can figure out your odometer error.
This past spring I use my Garmin eTrex Legend to check my speedometer. I discovered my speedo was showing 4-5 slower than actual speed or 3+ mph faster at 60 than indicated.
I changed from a 33 to 31 tooth gear, I have BFG AT LT235/75R15 tires. My speedo was on the money. I took one of my 450 mile trips to St Louis and discovered my odometer was racking up more miles.
The odometer in my GPS said I was recording 108 miles for every 100 miles traveled. When I got back I stuck the 33 tooth gear back in. I'd rather have an accurate odometer, I can live with a 4-5% error in the speedo.
So for you guys having gas mileage problems verify your odometer. Once you know or have fixed your odometer then you will know your true MPG.
This past spring I use my Garmin eTrex Legend to check my speedometer. I discovered my speedo was showing 4-5 slower than actual speed or 3+ mph faster at 60 than indicated.
I changed from a 33 to 31 tooth gear, I have BFG AT LT235/75R15 tires. My speedo was on the money. I took one of my 450 mile trips to St Louis and discovered my odometer was racking up more miles.
The odometer in my GPS said I was recording 108 miles for every 100 miles traveled. When I got back I stuck the 33 tooth gear back in. I'd rather have an accurate odometer, I can live with a 4-5% error in the speedo.
So for you guys having gas mileage problems verify your odometer. Once you know or have fixed your odometer then you will know your true MPG.
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