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Evaluation of a motor vehicle oxygen sensor performance

  • US 6,539,784 B1
  • Filed: 07/12/2000
  • Issued: 04/01/2003
  • Est. Priority Date: 07/12/1999
  • Status: Expired due to Term
First Claim
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1. A method for evaluating the performance of an oxygen sensor that detects an oxygen concentration level in an exhaust gas from an internal combustion engine, the method comprising:

  • cutting off a fuel supply to the internal combustion engine and allowing the detected oxygen concentration level of the exhaust gas to rise;

    reinstating said fuel supply after the detected oxygen concentration level has risen above a pre-determined upper threshold;

    measuring a fall time for the detected oxygen concentration level to fall to a pre-determined lower threshold from the moment said fuel supply is reinstated; and

    producing an oxygen sensor degradation signal if said measured fall time exceeds a pre-set time.

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