O2 Sensor Heater Issue All 4 Bad at Once?

[rcarson25]

I had a check engine light come on the other day on my 2012 Expedition Limited EL with 75000 miles on it. When I pulled the codes there were originally 6 codes, P0135; P0141; P0155; P0161 and then two that had to do with Bank 1 heater circuit getting low volts. I have never had all 4 O2 sensors go at the exact same time so I am a bit hesitant to go throwing 4 new O2 sensors at the problem only to find out I should be looking at something else first. Is there a HEGO fuse or anything like that I should be checking before breaking the bank on 4 new sensors, is it normal for all 4 to go at once? Thanks in advance.

 

[1955moose]

The chance of all 4 going out at once would be rare. Did you or anyone else do any repair or electrical add on recently? I don't have a wiring and fuse schematic for your SUV. Your owners manual should have all fuse/ relay locations if that's where you want to start. I'm sure one of the other guys here can help with wiring diagnosis. Don't start throwing parts at it, without a little ammunition first!


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[rcarson25]

The chance of all 4 going out at once would be rare. Did you or anyone else do any repair or electrical add on recently? I don't have a wiring and fuse schematic for your SUV. Your owners manual should have all fuse/ relay locations if that's where you want to start. I'm sure one of the other guys here can help with wiring diagnosis. Don't start throwing parts at it, without a little ammunition first!


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I would think this would be rare as well. I looked at the fuse/relay schematic for both the in cabin and underhood panel but I did not see anything that related to the O2 sensors. I did however find a blown power pass seat fuse but I am sure that is completely unrelated. No electrical changes have been made to the vehicle, in fact the last time I touched it was about 2000 miles ago for an oil change. I was going to do a big 75K mile service here soon, but want to figure this issue out first.

 

[rcarson25]

So, I searched around to see if there were any vacuum leaks or loose sensors that were obvious and I found nothing. However, for some reason the light went off. I have no idea why, but I am wondering if it had to do with the fact the weather warmed up. I will see if it comes back on as our temp drops this week, but I am happy at least for now that it is off.

 

[1955moose]

I hope for your case it does go away, but like a pain or hurt on our bodies it probably will come back. I guess if it's not affecting the running of your vehicle, and your smog is not due in the immediate future, it's up to you how much time and money you want to throw at it.


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[rcarson25]

So, cold weather is back and the light is on again. Is anyone on this forum familiar with the HEGO system and why this might be happening?

 

[rcarson25]

Does anyone know of a relay or a fuse tied to the HEGO system in a 2012 expedition? I have looked in the owners manual and searched but have come up empty so far.

 

[stamp11127]

I looked at wiring diagrams for a 2007 since I don't have them for the 2012. At that time there are 4 wires for each sensor, no relays but one fuse for all of them and branch circuits.

Without having diagrams the best thing for you would be to test all the fuses per the link in the electrical section on here. Using the tool(s) also lets you know if the fuse is getting power.

Do you have basic electrical knowledge and a dmm or test light?

 

[rcarson25]

I have the knowledge, but not the test light I will have to pick on up. Do you know where the fuse is located? Undressed or pass kick panel? I would assume 2007 and 2012 are the same.

 

[stamp11127]

Sent you a pm.

The only thing you can assume with Ford is nothing is the same from year to year. On one hand it is a good thing since it forces you to look up the correct information for the year.