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Home >> Geo >> 1995 >> Prizm Base, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Engine Controls - System/Component Tests - 1.8L) >> Diagnostic Charts >> Chart C-1D, Sub-Heated Oxygen Sensor (Ho2S) Heater Check. >> Notes
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Chart C-1D, Sub-Heated Oxygen Sensor (Ho2S) Heater Check.: Notes

WARNING: This page is about a different variant/trim than selected.

Sub-Heated Oxygen Sensor (sub-HO2S) has a built-in heater. This heater promotes activation of oxygen sensor to aid in improved fuel control during engine warm-up. PCM 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/Red wire.
  2. Checks for an open or a short to ground in Blue/Black wire between PCM and sub-HO2S or for a faulty sub-HO2S.
  3. Check for a faulty sub-HO2S or for a faulty PCM.