1994 Mitsubishi Eclipse Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Code 11: Oxygen Sensor (O2S) (2-Wire Oxygen Sensor)

NOTE: For component terminal identification, see TERMINAL IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.
  1. If using scan tester, go to step 2). Start and warm engine to operating temperature. Disconnect O2S connector. Connect DVOM between chassis ground and O2S terminal No. 1. While repeatedly racing engine, measure O2S output voltage. If voltage is not .6-1.0 volt, replace O2S. If voltage is within specification, go to step 4).
  2. Using scan tester, read O2S voltage. While monitoring scan tester, accelerate to 4000 RPM. Suddenly decelerate. Scan tester should read .3 volt or less. Suddenly accelerate. Scan tester should read .5-1.0 volt. If voltage is not as specified, replace O2S. If voltage is as specified, go to next step.
  3. While monitoring scan tester, accelerate to 2000 RPM and decelerate to 700 RPM (idle). Scan tester should switch between .6-1.0 volt and .4 volt or less. If voltage is not as specified, replace O2S. If voltage is as specified, go to next step.
  4. Disconnect O2S connector and ECM connector. Using DVOM, check for continuity between O2S terminal No. 1 and ECM connector terminal No. 4. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  5. Using DVOM, check continuity between chassis ground and O2S connector terminal No. 2. If continuity does not exist, replace O2S. If continuity exists, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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