DTC 27 - Sub-Oxygen Sensor Signal

DTC 27 is set when the main oxygen sensor signal is .45 volt or greater and sub-oxygen sensor signal is .45 volt or less when engine coolant temperature is at 176°F (80°C) or greater with accelerator pedal fully depressed for greater than 2 seconds.

Check for open or shorted circuit in sub-oxygen sensor circuit, a faulty sub-oxygen sensor or ECM.

Fig 1: DTC 27 - Schematic

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Fig 2: DTC 27 - Detection Driving Pattern

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Fig 3: DTC 27 - Diagnostic Flowchart

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