The resistance of the sensor and ECM after very very high in relation to the wires going to/from the sensor such that the wires are negligible.

The O₂ sensor generates a voltage based on the relative O₂ content of the air inisde the exhaust and the reference sample of O₂ in the wire lead coming into the sensor outside the exhaust.

That voltage travels down the lead wires at nearly instantaneous speed: roughly 180,000 miles per hour or 1/3600 the speed of light. It's effectively inside the ECU electrically.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)