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Home >> Geo >> 1995 >> Metro Base, 2D Hatchback >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 1.0L 3-CYL >> Diagnostic Charts >> Chart C-1D, Heated Oxygen Sensor (Ho2S) Check >> Notes

Chart C-1D, Heated Oxygen Sensor (Ho2S) Check: Notes

Heated Oxygen Sensor (HO2S) has a built-in heater. This heater promotes activation of oxygen sensor to aid in improved fuel control during engine warm-up. ECM turns heater on (to activate oxygen sensor heater) when engine is running without a heavy load or a high speed condition.

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. Checks for an open in Black/White wire.
  2. Checks for an open or short to ground in Pink/Black wire between ECM and HO2S or for a faulty HO2S.
  3. Checks for a faulty HO2S or for a faulty ECM.
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