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If there is oil at the computer end of the harness, then it could well be an issue.
But, if it is only at the sensor end, I would replace the sensor, ensure the harness is clean, and monitor the cars performance.
I would do as I have mentioned above.
Oil is a conductor as far as sensor voltages are concerned.
Especially if he feels the oil is at the computer end.
Seen this many times on many different cars.
Clean the connectors with electrical contact cleaner, and replace the sensor.
I hope this is a relatively easy economical repair for you.
Merry Christmas to you and your family.