Battery acid and harness warning plus O2 info | Ford Explorer Forums - Serious Explorations

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Battery acid and harness warning plus O2 info


June 27, 2015
Reaction score
City, State
Loomis, California
Year, Model & Trim Level
2013 Explorer Sport +402A
Late last year my 2013 explorer sport starting having cascading electrical failures. First was a cat error and then over the next few weeks I saw, O2 errors, A/C failure, charging system warnings and 4WD/PTO errors. To cut a long story short, the source of the failures was an acid damaged engine harness that went unnoticed for obviously a long time. While I had seen evidence of battery acid leakage over the years, I never saw anything that I would call serious. The issue here is that the affected harness and connector is right below the battery tray and hidden by the airbox. Acid dropping from the battery basically landed directly on the harness and over time, swelled the wires, made them brittle and breaking which then led to the various failures. So my warning is if you have seen any evidence of battery acid corrosion, I'd strongly suggest you remove the air box (two screws) and take a look at the harness/connector and clear it of any acid before it becomes a nightmare.

At first I thought I could repair the end of the harness with a new pigtail and connector I would build. I did manage to source new connectors, but once I got into it, it became clear that the damage to the harness was too extensive. Eventually I realized I had to replace the whole harness and what a ***** of a job it was as the harness wraps around, over and under the engine. But its done and everything is back to working and I just got a California smog done. I should note that the new harness now comes with a protective cap over its wires - too odd ;-)


PS While I'm at it, here is some O2 info I made notes of along the way. While I saw bits and pieces of this info in doing searches here, I didn't see all this info in one place. Sorry if I missed it.

Ford description: “Universal Heated Oxygen Sensor (UHO2S)”
Electrical descriptions: 5 wire, Sensor 1
Location descriptions: Upstream/Pre cat/Upper

Ford # 8F9Z-9F472-H
Motorcraft # DY-1185
BOSCH# 0-258-017-322

Ford description: “Heated Oxygen Sensor (HO2S)”
Electrical descriptions: 4 wire, Sensor 2
Location descriptions: Downstream/Post cat/Lower

Ford # BA5Z-9G444-A
Motorcraft # DY-1167

Lastly, Bank 1 is rear, near the firewall (as per cylinder #1). Bank 2 is front, behind front bumper.

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