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Oxygen Sensor

  1. Connect an exhaust gas analyzer to test point. Warm engine to operating temperature. Disconnect oxygen sensor wire. Note CO% level.
  2. Disconnect and plug the vacuum hose from the fuel pressure regulator. The CO% level should increase. Reconnect the oxygen sensor wire. The CO level should decrease to 0.6-1.0% (911 Carrera), or 0.4-0.8% (944). If not, test the DME control.
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