For starts...2002 Ford F150, 4.6l, 4x4

Check with the code reader and showing P0135 and P0155
Changed the O2 Sensor (upstream) and dead fuse.
I cleared the codes, took it out for a run and I'll still showing codes P0135 and P0155. What gives?

 

What gives is the fuse
likely blew again because there is a short to ground or an open in the harness at some point.
Get under and take a look for an exhaust burn-through or rub-through.
It could also be an open or a cross.
The codes are one for each bank so they are both in trouble.
If it was fuse 23, you should get a boat load of codes because that fuse feeds a lot of functions.
Good luck.

 

The fuse was #19 and is still good after all day driving. I cleared the code at the end of the day and started it up and the service eng came back on with 2 same code.

 

Fuse 19 had nothing to do with the Ox sensors.
So you lucked out on that.
The codes are telling you the OX sensors 'heater circuits' are in trouble.
These heaters shorten the time it takes the motor to settle back to normal idle from a cold start and keeps them hot for the averge running time and loads.

 

..I started looking for a burnt fuse at the bottom and 19 was the first one I came to Guess I need to check them all. Thanks for the help

 

According to my 2003 manual, fuse #19 in the PDB is for right stop/turn bulb on the trailer plug, fuse #19 in the in-cab box is not used.

Bluegrass mentioned fuse #23, that's in the PDB, and it's for HEGO sensors and automatic transmission. That's the only fuse that I see having to do with the sensors, but I don't have a detailed wiring diagram, I'm just going by the description in the manual.

Don't you have an owner's manual? If not, download it.

https://www.fleet.ford.com/maintenance/owners_manuals/

 

Thanks, I do have a manual but wasn't sure what fuses to check... I did check them all and everyone is good.
Codes are still showing...I did fail to mention I do have code P0403 as well but didn't think it had anything to do with both codes mentioned above.

 

The 403 code is an EGR circuit error involving the DPFE electrical circuit.
While it's not related to the OX sensors, it suggests it could be a harness issue again, where the wires physically come togather.
Good luck.

 

Thanks again Bluegrass
Guess I will be doing some wire harness probing. Luck is what I need

 

Just realized there are 2 O2 sensor's! I did ask the dealer if there was 2 upstream and he say "no, just one" today the other guy told me 2. So now I wait to get the other one tomorrow.

 

There are two OX sensors , one each side just down stream from the exhaust manifolds.
They control fueling for each bank.
The other two are in each rear cat for monitoring the cat system health.
Good luck.

 

Well, at lease I changed to hard one (passenger side) I have better access to the one on the drivers side.

 

Both upstream O2 Sensor changed.
Still getting
P0135 (Heater Circuit - Bank 1, Sensor 1) & P0155 (O2 Heater Circuit - Bank 2, Sensor 1)

 

That sounds like a short for sure. If they came back right away. That means the monitor attempted to run but was stopped right away. Those heaters fire up as soon as you hit the key. When in doubt, take a picture first, if that helps lol, -then keep pulling fuses. Ford changed fuse locations/wiring year to year. So pay attention to that guy with the 02. What was his name ? Bluegrass, that's right. . GLC can't be too far off, but as much as Ford moved everything around per model year and with engine differences, you can't be sure unless you have the manual. There really isn't a general wiring diagram form these trucks. It's one very good reason for having your owners manual in the GLOVE BOX at all times. It's all in there..

 

I think your missing an important point on this.
The problem is not a short but an 'open'.
If it was a short, you would have blown fuse 23 and had all kinds of codes from it.
All you needed to do was test the sensors with a low cost meter for being open and verify the missing voltage and you would have found them good for their heater continuity and not have the change them until later, if you still wanted to after finding the open fault.
Never test the 'sensor' leads with even an ohm meter, only the heater leads.
Of course the PCM will see the open right away because it looks at the current draw.
These sensors are part of the system at all times.
The fact that both are open tells me the harness is cut or worn open at some common point between the fire wall, down the pass side of the motor back to the sensors.
In this harness is the transmission control, the EVAP and neutral control leads.
Where the leads break out of the harness separate; from that point on is likely to be the trouble area.
Check for voltage to the rear sensors and see if it's there.
That will further narrow the area down.
Was there any other work done under the truck?
Good luck.