ALL 3 O2 Heater elements went bad at same time!

[r37ribution]

I have a '96 explorer with 189,000 miles on it and suddenly I got a check engine light. So I promptly took it to the local auto parts store to run a scanner on it. It came up:
bad O2 heating element Bank 1, Sensor 1
bad O2 heating element Bank 1, Sensor 2
bad O2 heating element Bank 2, Sensor 1

which I thought was kinda odd that ALL 3 O2's would go bad at the same time, but I didn't know when they were done last cuz I hadn't done them and I bought it with 155,000 miles. So I replaced all 3 O2 sensors, cleared the codes, the check engine light stayed out for about 2 min and then all 3 of the exact same codes for the O2's returned! So I'm assuing that I don't have 3 brand new O2's that are shot, so this must be some sort of heating element circuit issue? Has anyone seen this before? Any ideas of where to start looking?

 

[r37ribution]

anyone had this problem with the heating element before? got any ideas???

 

[Opera House]

Hmmmmmmmmm, heating element. Sounds like the fuse has blown that supplies power to the internal heating element of the O2 sensor.

 

[Runnin'OnEmpty]

Opera House is correct, there's a fuse that protects this circuit. It should be in the underhood box on the driver's side.

The wiring harness for the bank 1/sensor 2 runs over the catalytic converter. Check to see if the wiring has fallen onto the converter and melted, causing a short. If the wiring is shorted onto the converter, that would have blown the O2 heater circuit fuse.

 

[r37ribution]

dude I been trying to solve this forever...I didn't have email notification turned on and I thought I did so I never checked this post. I'll check this tonight THANK YOU for the replies! 11.5mpg SUCKS!

None of the old O2 wires showed any sign of damage and I just checked the new ones yesterday and they are intact...but these were put on after the problem came up.

 

[r37ribution]

ok I checked the owners manual since the fuse box under the hood is useless as far as labels go. I could not find anything that sounded like it would be relavant to the oxygen sensors. anyone have any idea what the fuse would be labeled? i haven't got around to checking all of them yet, but if anyone knew what it would be labeled that would help.

 

[r37ribution]

:update:

It was a fuse! omg I have been suffering 11.5 mpg for the last 5 months because of a damn fuse!

It's labeled HEGO in the owners manual and its located amoungst the relays and is the closest fuse to the front of the vehicle in the engine compartment fuse box

 

[Opera House]

No one ever listens to me.

 

[r37ribution]

No one ever listens to me.

Dude! I did listen to you! you were my 11.5mpg savior! lol

I didn't have email notification turned on so I never got the replies to this post. BELIEVE ME I WISH I WOULD HAVE.

I have driven 3,000 miles on 11.5 mpg since my first post about this. Filling up at an average of $1.90 since then thats almost $500 I have spend on gas. If I would have been getting an average of 16mpg it would have only been $360 out of my pocket.

Such a costly fuse!!!!

:edit:
what kinda milage do you get with YOUR 4.0L OHV trucks?

 

[Runnin'OnEmpty]

R37, I get about 18 in town, 21+ on the highway. Average is about 20. This is with an OHV 2WD Sport, similiar to yours.

Glad you found that fuse. A short circuit caused the fuse to blow, from either bad O2 wiring or a short in an O2 heater itself. Either way, it sounds like you fixed it.

 

[Glacier991]

Now OperaHouse - I never fail to credit your good judgment (smile)....

 

[Eneurb]

I can't remember if this problem effected OHV engines, but on the SOHC, there is a heatshield around the Y pipe that the O2 sensor goes through. Sometimes that heatshield falls off of the pipe and hangs on the wires to the bank 2 upstream sensor and wears through causing a short. I am a firm believer that fuses don't just blow, there is always a reason.

 

[r37ribution]

I checked the Y pipe heatshield on the driver side and passenger side just before the 2 pipes come together at the 1st cat. they were a little loose but I tried to bend them and it wouldn't move much at all. Now on the passenger side the O2 wires did have a LOT of slack on the new O2 sensor so I used a zip tie to tidy it up a lil bit. I believe that it would have rubbed against the exhaust mani if I would have left it. I don't remember any burn marks on the O2 sensor's wires when I replaced them.

Eneurb: I agree that if a fuse blows you definately need to do some research, but I have seen a few fuses blow on the arcade games/slot machines/pinball machines/jukeboxes for no apparent reason (and they don't blow again) so I'm just gonna keep my fingers crossed. Besides I can't find a reason for it to blow and it hasn't since. Maybe 192,000 miles could do that to an old fuse?