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Oxygen Sensor

  1. Disconnect oxygen sensor connector. Start engine and warm-up for 2 minutes at 3000 RPM under no load. Raise engine speed to 4000 RPM and release throttle suddenly at least 5 times.
  2. Within 1 minute after engine has been warmed up, measure voltage between connector terminal and body ground as outlined in steps 3) and 4).
    NOTE: If it takes more than 1 minute to complete checks, warm-up engine as outlined in step 1.
  3. Raise engine speed to 5000 RPM, then lower to 2000 RPM. Immediately turn ignition off. Voltage at terminal should be less than 0.4 volts. Disconnect vacuum hose No. 21 (hose between throttle body and MAP sensor on Civic CRX Si), at throttle body. Plug throttle body fitting.
  4. Connect vacuum pump to open end of vacuum hose. Apply 12 in. Hg vacuum and raise engine speed to 4000 RPM. Voltage reading should be more than 0.6 volts. Replace O2 sensor if voltages are not within specifications.
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