O2 Sensor

Hickory94 · 12-26-2003, 09:01 PM

I am going to replace my cracked header with a Banks, my TJ has roughly 72,000 on it I was thinking about replacing the O2 sensor...come to find out there are 2 one b4 the converter and 1 after...1 is 70.00 the other is 80.00.
Would I replace the one b4 the converter or both..or not at all....I dont have a code reader so I dont know if I am pulling any codes.

Thanks

StealthTJ · 12-26-2003, 09:27 PM

If either the upstream, or the downstream O2 sensor is "bad", it'ld cause the "Check Engine Light" to come on.
The upstream O2 sensor is often replaced at around the milage you have on your Jeep now, just to make sure that it's operating at peak condition.

Fred

mfox · 12-28-2003, 03:53 AM

If your O2 sensor causes the check engine light to come on.....it's pretty much dead. But you can have a lazy O2 sensor that will make your engine not run at it's peak, with no check angine light. Those O2 sensors can be tested with a lab scope or graphing multimeter. I prefer to test them instead of replacing. It is too expensive to replace just because you think it's time. My TJ has 68k on it right now and I just tested both of my O2's and they are working just like a new one would. It would be a waste of money to put new ones in. I know most people don't have a lab scope or graphing multimeter here, but your local quality auto repair shop does. Probably still cheaper to have someone test them as opposed to taking the shotgun replacement method.

Nighthawk98TJ · 12-28-2003, 04:03 AM

I've got almost 47,000 miles on my TJ and was thinking I may have an O2 sensor that is having issues since I'm getting hesitation when accelerating on the freeway onramps and my gas mileage is in the mid-13's tops, usually a tad lower.

Are there any other ways to test the sensor at home?

cabletow · 12-28-2003, 05:12 AM

A bad sensor will throw a code if you get the codes checked, (do the on off thing wih the key in a 97 or use a OBD thing otherwise). A bad sensor does not necessarily mean the check engine light comes on. It is worth getting the codes checked from somewhere. Replacing the sensor will cure your hesitation problem but dont ecxpect big milage returns.

Jeepin_Jeffster · 12-28-2003, 09:14 AM

Yes, it's possible you'll get big mileage returns. When I replaced a faulty O2 sensor in my ZJ 4.0L at 115K miles, my mileage went up 4-5 MPG!! It won't take many tanks of gas to pay for the cost of the sensor at that difference.

StealthTJ · 12-28-2003, 10:41 AM

Quote:

-=- originally posted by cabletow -=-
A bad sensor will throw a code if you get the codes checked, (do the on off thing wih the key in a 97 or use a OBD thing otherwise). A bad sensor does not necessarily mean the check engine light comes on. It is worth getting the codes checked from somewhere. Replacing the sensor will cure your hesitation problem but dont ecxpect big milage returns.

On '98's (which is what I have and have the FSM for),
*ALL* O2 failures that set a code also illuminate the MIL (turn on the "Check Engine Light"), so, for '98's at least, your statement is not true.

A "weak" O2 sensor will not set any codes.

Fred

[EDIT], Opps, just noticed that I had typed "CO2" and meant to type "O2"

Nighthawk98TJ · 12-28-2003, 02:27 PM

Interesting information. Sounds like a gamble to see whether or not, in my case, it fixes any problems.

Jeepn' 4 Life · 12-28-2003, 03:11 PM

How much does it cost to replace an O2 sensor? The sensor in my wife's '97 is bad.

Special Ed · 12-28-2003, 04:08 PM

might want to cgheck out bosch premium O2 sensors, around 30 each

Nighthawk98TJ · 12-28-2003, 04:18 PM

The Bosch ones locally seem to be around $85 for me... OxygenSensors.com has them for the TJ for about $53 with free shipping (not Bosch).

I thought I remembered reading something a while back about unplugging the O2 sensor to test it and letting it throw the check engine light, but drive it unplugged to see if things are better. Is this correct or am I thinking of something else?

Personally, my main concern is getting my gas mileage back up... something is definitely not right as it has been decreasing over the past year and now I get this hesitation when accelerating... if I stand on the pedal I don't really feel it though.

mfox · 12-29-2003, 01:26 AM

Unplugging the O2 sensor is not recommended. It will do nothing for you other than throw a code and make the engine run either lean or rich. When you plug it back in it will just go back to doing whatever it was doing before. Not much point in it.

Nighthawk98TJ · 12-29-2003, 01:29 AM

Quote:

-=- originally posted by mfox -=-
Unplugging the O2 sensor is not recommended. It will do nothing for you other than throw a code and make the engine run either lean or rich. When you plug it back in it will just go back to doing whatever it was doing before. Not much point in it.

I see. Thanks for the information.

cliffslocal · 12-29-2003, 01:49 AM

Dude, this is the cheapest place
http://www.tapcointernational.com/st...OXYGEN++SENSOR
and Autozone will let you borrow a O2 sensor wrench for free

mfox · 12-29-2003, 04:13 AM

Another note about oxygen sensors. I deal with a lot of repair shops and hundreds of repair technicians every week for a living. If you talk to the better driveability techs they will tell you that there is nothing better the the factory original O2 sensor. Many aftermarket ones are not either calibrated correctly or they are made of inferior product or workmanship. I have personally seen this in a Chevrolet pickup I once had. It would go through an O2 sensor every year when I was using ones from NAPA. Switched to a factory AC Delco and it went for years. This was very common. My point here is that you may find them cheaper, but they may not be very good ones. As far as an aftermarket O2 sensor goes, I would probably give the Bosch ones a try. Other than that I don't trust any of them unless it's the factory unit. This is not the only sensor on a vehicle that I have noticed these problems with either.

Rick 601 · 12-29-2003, 08:47 AM

On the AUDI, the "factory" sensor is 170. An aftermarket Bosck is 38 (from napa) they are the SAME sensor- only the wiring harness is different. You will want to see that your replacement has the same # of wires as the factory one (some are heated and have 4 wires, some 3 and some 2 even 1 I think) Then just solder splice the new one in- keep the wires the same length as original, we're dealing with very small amounts of electricity. For me the $40 savings is worth it- maybe you can afford to step over a couple of double sawbucks- I can't.

BTW you can test a sensor with a multi-meter.

Finally- get the special slotted socket if you can- you can TRY an open ended box wrench if there is room to swing it- but you won't get many chances to not strip the base- it can get ugly. The wrench is 12 at NAPA (probably 1.50 at harbor freight!lol) whoopie another tool!!

mfox · 12-29-2003, 09:43 AM

Yes, you can test an oxygen sensor with a multimeter. It will tell you if it's dead or alive. But it's not accurate enough to tell you if it's lazy or slow reacting. You need a live pattern of a lab scope that can plot over a time base to see that. Rick 601 may have found a way to save a few bucks by soldering the old plug onto a new sensor.... I don't think many of us here will be that brave.

Rick 601 · 12-29-2003, 10:23 AM

I used shrink tube and pretty basic soldering- by the 4th one I realized that I should stagger the joints- mine were 3 and 4 wire.

The soldering was tinned wires side to side- not all twisted together. I was leery of butt connectors- didn't know if it'd effect voltage- anyone??

Jeepin' Geo · 12-31-2003, 12:40 PM

Quote:

-=- originally posted by mfox -=-
If your O2 sensor causes the check engine light to come on.....it's pretty much dead. But you can have a lazy O2 sensor that will make your engine not run at it's peak, with no check angine light. Those O2 sensors can be tested with a lab scope or graphing multimeter. I prefer to test them instead of replacing. It is too expensive to replace just because you think it's time. My TJ has 68k on it right now and I just tested both of my O2's and they are working just like a new one would. It would be a waste of money to put new ones in. I know most people don't have a lab scope or graphing multimeter here, but your local quality auto repair shop does. Probably still cheaper to have someone test them as opposed to taking the shotgun replacement method.

mfox,

Can you elaborate on the procedure for testing the O2 ensors with a scope? I have access to a 100mhz dual channel storage scope if that is any help.

I have FOUR of these little buggers in my '01, so it would be nice to be able to test them rather than just shotgun a suspected issue.

Thanks,

****** and ******

Happy New Year to all!

DEN · 12-31-2003, 02:06 PM

Quote:

-=- originally posted by Special Ed -=-
might want to cgheck out bosch premium O2 sensors, around 30 each

Be careful, Bosch didn't fit mine right (didn't go all the way in to engage threads). I ended up coughing up the $130 for a dealer Mopar one.

Ran smoother, cleaner, and better MPG. I wish I had done it a year earlier.

12-26-2003, 09:01 PM	#1
Hickory94 Registered Join Date: Apr 2001 Location: Mundelein, IL USA Posts: 290 Thanks: 0 Thanked 0 Times in 0 Posts	O2 Sensor I am going to replace my cracked header with a Banks, my TJ has roughly 72,000 on it I was thinking about replacing the O2 sensor...come to find out there are 2 one b4 the converter and 1 after...1 is 70.00 the other is 80.00. Would I replace the one b4 the converter or both..or not at all....I dont have a code reader so I dont know if I am pulling any codes. Thanks __________________ 98 TJ (Firewalkers Jeep Club)firewalker4x4.org RE 4.5 SF \| 34X10.5X15 LTB's \| ORO U-Turn Kit \| Rock Ready Steering Skid \| JKS \| D30-ARB \| 8.8-Discs-ARB \| 4.10's \| AA SYE-Tom Woods CV DS \| D30 Warn Guard \| Warn Front Bumper \| Superwinch EPI 9000 \| Jeeperman Rear W/Tire Swing \| Banks Header \| [b]Dynomax Catback \| Nth Degree SS \| Off your Rocker crush guards W/ flush LED's \| Herculined \| Or-Fab Rollcage \| Cobra/Firestik \| K&N \| Tomken Rocker Guards \| Warn Gas Skid \| \| \| Optima ------------------------------------------------ 99" Grand Cherokee Limited 4.7L \| Stock \| Hers ------------------------------------------------ 2001 Silverado 2500HD Tow Vehicle \| Daily Driver \| Finaley get to park the Jeep and use if for trails

12-26-2003, 09:27 PM	#2
StealthTJ Registered Join Date: Jul 2000 Location: Tucson, AZ USA Age:60 Posts: 4,498 Thanks: 0 Thanked 0 Times in 0 Posts	If either the upstream, or the downstream O2 sensor is "bad", it'ld cause the "Check Engine Light" to come on. The upstream O2 sensor is often replaced at around the milage you have on your Jeep now, just to make sure that it's operating at peak condition. Fred __________________ Fred Wilson Base - '98 Sahara, 4.0L 6 cyl, Auto (swap from 5 sp) Suspension - 4.0" Procomp Springs + 1 1/4" JKS body lift. Rear tri-link. Currie J arms in the rear. HPD30, front axle, With Currie J-Arms, WJ knuckles, WJ dual piston calibers, Warn Hub Kit, with Warn inners, and CTM u-joints. Cross over, hi-steer. Currie Anti-Rock Sway Bar. Axles & Lockers - Dana30/Dana44 (rear disk conversion); LockRite/Full Detroit; 4.56. Drivetrain - AA SYE and CV Driveshaft, Tera 2wd lo. Armor - Full Wheels - 35x12.50 MT/R's sipped on 15x7 Champion Beadlocks. Recovery - Warn XD9000i

12-28-2003, 04:03 AM	#4
Nighthawk98TJ Registered Join Date: Jun 2002 Location: Santa Rosa, CA - 165.18 miles from 'The Rubicon' Posts: 2,302 Thanks: 0 Thanked 0 Times in 0 Posts	I've got almost 47,000 miles on my TJ and was thinking I may have an O2 sensor that is having issues since I'm getting hesitation when accelerating on the freeway onramps and my gas mileage is in the mid-13's tops, usually a tad lower. Are there any other ways to test the sensor at home? __________________ Northern California Ridge Raiders 1998 Jeep Wrangler (TJ) 2.5L Automatic RE 3.5 · JKS 1.25" BL · 35" Cooper STT's · D30 Lockright · Yukon 35 + Detroit · Many Other Mods "The end is never as satisfying as the journey. To have achieved everything but to have done so without integrity and excitement is to have achieved nothing." --Author unknown

12-28-2003, 05:12 AM	#5
cabletow Registered Join Date: Sep 2002 Location: UK or engerland as it is known on the terraces Posts: 1,460 Thanks: 0 Thanked 0 Times in 0 Posts	A bad sensor will throw a code if you get the codes checked, (do the on off thing wih the key in a 97 or use a OBD thing otherwise). A bad sensor does not necessarily mean the check engine light comes on. It is worth getting the codes checked from somewhere. Replacing the sensor will cure your hesitation problem but dont ecxpect big milage returns. __________________ From the home of warm beer

12-28-2003, 02:27 PM	#8
Nighthawk98TJ Registered Join Date: Jun 2002 Location: Santa Rosa, CA - 165.18 miles from 'The Rubicon' Posts: 2,302 Thanks: 0 Thanked 0 Times in 0 Posts	Interesting information. Sounds like a gamble to see whether or not, in my case, it fixes any problems. __________________ Northern California Ridge Raiders 1998 Jeep Wrangler (TJ) 2.5L Automatic RE 3.5 · JKS 1.25" BL · 35" Cooper STT's · D30 Lockright · Yukon 35 + Detroit · Many Other Mods "The end is never as satisfying as the journey. To have achieved everything but to have done so without integrity and excitement is to have achieved nothing." --Author unknown

12-28-2003, 03:53 AM	#3
mfox Registered Join Date: Oct 2002 Location: Bellingham, WA. Posts: 423 Thanks: 0 Thanked 0 Times in 0 Posts	If your O2 sensor causes the check engine light to come on.....it's pretty much dead. But you can have a lazy O2 sensor that will make your engine not run at it's peak, with no check angine light. Those O2 sensors can be tested with a lab scope or graphing multimeter. I prefer to test them instead of replacing. It is too expensive to replace just because you think it's time. My TJ has 68k on it right now and I just tested both of my O2's and they are working just like a new one would. It would be a waste of money to put new ones in. I know most people don't have a lab scope or graphing multimeter here, but your local quality auto repair shop does. Probably still cheaper to have someone test them as opposed to taking the shotgun replacement method.

12-28-2003, 09:14 AM	#6
Jeepin_Jeffster Registered Join Date: Dec 2003 Location: Eastern NC Posts: 377 Thanks: 0 Thanked 0 Times in 0 Posts	Yes, it's possible you'll get big mileage returns. When I replaced a faulty O2 sensor in my ZJ 4.0L at 115K miles, my mileage went up 4-5 MPG!! It won't take many tanks of gas to pay for the cost of the sensor at that difference.

12-28-2003, 03:11 PM	#9
Jeepn' 4 Life Registered Join Date: Nov 2003 Posts: 224 Thanks: 0 Thanked 0 Times in 0 Posts	How much does it cost to replace an O2 sensor? The sensor in my wife's '97 is bad.

12-28-2003, 04:08 PM	#10
Special Ed Registered Join Date: Sep 2002 Location: Macon, GA Posts: 1,198 Thanks: 0 Thanked 0 Times in 0 Posts	might want to cgheck out bosch premium O2 sensors, around 30 each __________________ 95 YJ 2.5L Low Output, AX-5, NP231 RE SYE/ RE CV-Shaft/ 4.0 Throttle Body/ SOA with 2 " PA body lift/ 33x12.50 Mud Rovers/ Black Rock Krawlers/ Air Raid T-body Spacer/ Rhino Lined Exterior & Interior/ Hardtop/ Alpine CD player/ Diamond Audio D3 600.1 & Diamond Audio CM3 12"/ Cheap Ass CB/

12-28-2003, 04:18 PM	#11
Nighthawk98TJ Registered Join Date: Jun 2002 Location: Santa Rosa, CA - 165.18 miles from 'The Rubicon' Posts: 2,302 Thanks: 0 Thanked 0 Times in 0 Posts	The Bosch ones locally seem to be around $85 for me... OxygenSensors.com has them for the TJ for about $53 with free shipping (not Bosch). I thought I remembered reading something a while back about unplugging the O2 sensor to test it and letting it throw the check engine light, but drive it unplugged to see if things are better. Is this correct or am I thinking of something else? Personally, my main concern is getting my gas mileage back up... something is definitely not right as it has been decreasing over the past year and now I get this hesitation when accelerating... if I stand on the pedal I don't really feel it though. __________________ Northern California Ridge Raiders 1998 Jeep Wrangler (TJ) 2.5L Automatic RE 3.5 · JKS 1.25" BL · 35" Cooper STT's · D30 Lockright · Yukon 35 + Detroit · Many Other Mods "The end is never as satisfying as the journey. To have achieved everything but to have done so without integrity and excitement is to have achieved nothing." --Author unknown

12-29-2003, 01:26 AM	#12
mfox Registered Join Date: Oct 2002 Location: Bellingham, WA. Posts: 423 Thanks: 0 Thanked 0 Times in 0 Posts	Unplugging the O2 sensor is not recommended. It will do nothing for you other than throw a code and make the engine run either lean or rich. When you plug it back in it will just go back to doing whatever it was doing before. Not much point in it.

12-29-2003, 01:49 AM	#14
cliffslocal Registered Join Date: Feb 2003 Location: san diego Posts: 444 Thanks: 0 Thanked 0 Times in 0 Posts	Dude, this is the cheapest place http://www.tapcointernational.com/st...OXYGEN++SENSOR and Autozone will let you borrow a O2 sensor wrench for free __________________ 97 TJ a few mods - sold:dmb: 92 YJ 32" maxxis, TJ flares, 1" BL "you ever take it off any sweet jumps"

12-29-2003, 04:13 AM	#15
mfox Registered Join Date: Oct 2002 Location: Bellingham, WA. Posts: 423 Thanks: 0 Thanked 0 Times in 0 Posts	Another note about oxygen sensors. I deal with a lot of repair shops and hundreds of repair technicians every week for a living. If you talk to the better driveability techs they will tell you that there is nothing better the the factory original O2 sensor. Many aftermarket ones are not either calibrated correctly or they are made of inferior product or workmanship. I have personally seen this in a Chevrolet pickup I once had. It would go through an O2 sensor every year when I was using ones from NAPA. Switched to a factory AC Delco and it went for years. This was very common. My point here is that you may find them cheaper, but they may not be very good ones. As far as an aftermarket O2 sensor goes, I would probably give the Bosch ones a try. Other than that I don't trust any of them unless it's the factory unit. This is not the only sensor on a vehicle that I have noticed these problems with either.

12-29-2003, 08:47 AM	#16
Rick 601 Registered Join Date: Mar 2000 Location: UPSTATE NY Posts: 1,208 Thanks: 0 Thanked 0 Times in 0 Posts	On the AUDI, the "factory" sensor is 170. An aftermarket Bosck is 38 (from napa) they are the SAME sensor- only the wiring harness is different. You will want to see that your replacement has the same # of wires as the factory one (some are heated and have 4 wires, some 3 and some 2 even 1 I think) Then just solder splice the new one in- keep the wires the same length as original, we're dealing with very small amounts of electricity. For me the $40 savings is worth it- maybe you can afford to step over a couple of double sawbucks- I can't. BTW you can test a sensor with a multi-meter. Finally- get the special slotted socket if you can- you can TRY an open ended box wrench if there is room to swing it- but you won't get many chances to not strip the base- it can get ugly. The wrench is 12 at NAPA (probably 1.50 at harbor freight!lol) whoopie another tool!! __________________ 2000 sport, ARB front locker, winch, armour, 2 1/2" suspension lift/ 1"coil, MM, BL, ARB Bumper, 33X11.2MT/R, Warn bumper/tire carrier, 4:56 and Power-lok, goferit belly-up , tera 2&4low, currie antirock, TBT "cage"etc..

12-29-2003, 09:43 AM	#17
mfox Registered Join Date: Oct 2002 Location: Bellingham, WA. Posts: 423 Thanks: 0 Thanked 0 Times in 0 Posts	Yes, you can test an oxygen sensor with a multimeter. It will tell you if it's dead or alive. But it's not accurate enough to tell you if it's lazy or slow reacting. You need a live pattern of a lab scope that can plot over a time base to see that. Rick 601 may have found a way to save a few bucks by soldering the old plug onto a new sensor.... I don't think many of us here will be that brave.

12-29-2003, 10:23 AM	#18
Rick 601 Registered Join Date: Mar 2000 Location: UPSTATE NY Posts: 1,208 Thanks: 0 Thanked 0 Times in 0 Posts	I used shrink tube and pretty basic soldering- by the 4th one I realized that I should stagger the joints- mine were 3 and 4 wire. The soldering was tinned wires side to side- not all twisted together. I was leery of butt connectors- didn't know if it'd effect voltage- anyone?? __________________ 2000 sport, ARB front locker, winch, armour, 2 1/2" suspension lift/ 1"coil, MM, BL, ARB Bumper, 33X11.2MT/R, Warn bumper/tire carrier, 4:56 and Power-lok, goferit belly-up , tera 2&4low, currie antirock, TBT "cage"etc..

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode