'99 limited SOHC troubleshooting feedback please!

['99_Limited]

Hi!
Love this forum and it's been a huge resource for me the last 2 months!
Here is my situation- just bought my second explorer a '99 limited with the 4.0 SOHC AWD 5R55E trans. (Had a 2000 XLT before) Truck was in great shape with the exception that the women that owned it did very little upkeep on it (basically not replacing regular maintenance items) it had a filthy interior/exterior and it was not running, would shutter and stall at take off. I Paid $1000 for it and luckily after doing some initial troubleshooting, coding and referencing this forum found that the only reason it wasn't running was because fuse 13 was blown. Replaced the fuse and drove it and it seemed fine so I proceeded to bring it back to its once glorious self- full tune up, new tires, replaced the display board in the Mach audio system, conditioned the leather, full scrubbing/cleaning and replacing a few missing or broken trim parts & outfitting it with a full THULE roof rack system. This is to be my daily commuter & play vehicle for paddling, biking, camping etc.
Drove it back and forth to work for a week and the truck ran great, getting about 17 miles to the gallon which I believe was on the window sticker. (These were state of the art when they first came out when I was about in my mid 20's and I remember my buddy at the time bought an Eddie Bauer edition brand new off the lot, I was extremely jealous & this is redemption!) then one evening the fuse blew again so I pulled over replaced it and the truck was fine for another week, fuse blew again replaced it stepped on the accelerator and that one blew. Luckily this was just a couple of miles from home so I limped it in.
As many of us know when fuse 13 blows the truck will throw about 9 codes this in addition to the EVAP large leak code. Figuring the truck could use fresh tranny fluid & filter so I pulled the pan and filter, tested the 6 solenoids which all fell within tolerable ranges, replaced the filter, gasket, filled fluid and moved onto the charcoal canister under the spare tire. Dropping the spare tire and down came the entire EVAP system! Apparently the bracket/shelf that holds the entire system up was completely rusted away with the exception of the 3 tabs that mount it to the cross rail and frame. I proceeded to try to remove the 3 bolts to replace this shelf with no success, so I sprayed some blaster, tried again, no go, sprayed more blaster, no go, sprayed more blaster then tested the canister solenoid and though very rusted fell within tolerable ranges I also had 13.6 volts at the electrical connector. Tried to pull the bolts again, no go sprayed more blaster and proceeded to make an improvised hanger for the EVAP system. I do not think ill be able to remove these bolts without professional help, plus I'll need to find a new one or one from a UPULL. Raised the spare, cleared the codes and took it for a country road ride and all was fine. Took it to work Monday and about 6 miles into the commute The CEL light came on. Got to work and coded it. The 2 codes that came up were P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1) & P1451 EVAP Control System Canister Vent Solenoid Circuit Malfunction (small leak detected) that night on my ride home at almost the exact same place as the first time... the fuse blew, I replaced it and it blew again 2 miles down the road. Again close to home so I limped it in and took the Hyundai to work the next day
I was however happy that I was able to get 2 isolated codes that morning and my question for anyone who is reading and willing to give some feedback is: since the O2 sensor code came up and since all 4 O2 sensors run on the same circuit and Bank 2 sensor 1 has a heater malfunction would it be likely that this sensor during malfunction is blowing fuse 13? And would the next logical step be to replace that upstream O2 sensor? Also, is this sensor on the driver side in front of the cat below the tyranny pan?
Thanks in advance for any help and thanks for all the help up to this point!

 

[Turdle]

Check the bank 2 sensor one wiring. It may be touching the exhaust, or even the front drive shaft.

This is the sensor right under the transmission. follow the wiring up, and check if it has enough slack to be hitting anything. You'll need to feel it by hand for cracking--bare insulation.

 

[2000StreetRod]

bank 1 definition

Bank 1 is always defined as the bank containing cylinder 1.

Sensor 1 is normally the pre-cat sensor and sensor 2 is normally the post-cat sensor. So yes, Bank 2 Sensor 1 is on the driver side (in the USA) and upstream of the cat.

 

['99_Limited]

Thanks fellas! Do you think I'm on the right track with this? I am gonna check the wiring harness tomorrow and I would bet with 170,000 miles these are most likely all original 02'sensors.

 

[2000StreetRod]

Fuse 13

Fuse 13 in the battery junction box provides power to the heaters of all 4 O2 sensors. The other heater wire for each sensor is connected to a PCM pin that I suspect monitors the current flow for each heater. If the supply to the heater was permanently shorted Fuse 13 would immediately blow. I suspect that Turdle's assessment is correct. The supply wire insulation has probably come in contact with the exhaust and burned off. When it flops up against the exhaust it shorts out and blows the fuse.

 

['99_Limited]

Spot on!

Not sure how I didn't notice this before! Especially with all the time I've been spending on my back under this vehicle! There is a small heat shield that covers the curve on this exhaust pipe that has a hole in it right at the port that the O2 sensor goes into, I knew it had come undone but what I didn't see was a small break in the insulation right at the collar of the harness coming off the sensor. I guess I would hit a bump and this shield would make contact with the exposed wire. I unhooked the harness and pulled the sensor (thankfully it took one good push on the wrench and I didn't have to wrestle with it!) slid the collar up, cut the cover and trimmed back the bad wire. I then soldered and heat shrinked it pulled the collar back up and electrical taped the ribbed plastic harness cover. Put 2 new pipe clamps on the heat shield and replace the repaired O2 sensor.
I'd checked this harness before but thanks to you guys throwing out these suggestions I went back under there with a more determined eye, this crack was right at the rubber collar filler and very hard to see. Once I even began to fiddle with it it immediately broke! There is no doubt that this was the cause of the issues and a big contributor to me getting a great price on this vehicle. At some point I will replace all 4 O2 sensors.

Now I've saved enough money trouble shooting this on my own that I can move on to replacing the conventional shocks she had installed last year which replaced the ARC shocks with new ARC shocks!

Thanks for the help guys!

 

['99_Limited]

Well, 2 days of driving with no issues, blown fuses or codes other than the p0442 small leak detected that keeps popping up!
Now on to the next thing......