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Home >> Mitsubishi >> 1994 >> Expo Base, AWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> Codes 59 & 69: Rear Oxygen Sensor (O2S)
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Codes 59 & 69: Rear Oxygen Sensor (O2S)

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 next step. Disconnect O2S connector. Using DVOM, check continuity between O2S terminals No. 3 and No. 4. If continuity does not exist, replace O2S. If continuity exists, go to step 3).
  2. With an assistant, road test vehicle. Drive vehicle with wide open throttle in 2nd gear (M/T) or "L" position (A/T). Using scan tester, read O2S voltage. If O2S voltage is not .6-1.0 volt at 3500 RPM, replace O2S. If voltage is as specified, go to next step.
  3. Disconnect O2S connector and MFI relay connector. Using DVOM, check for continuity between O2S connector terminal No. 3 and MFI relay connector No. 2. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  4. With O2S connector disconnected, disconnect ECM connector. Check for continuity between O2S connector terminal No. 1 and ECM connector terminal No. 55. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
  5. With O2S connector disconnected, check for continuity between chassis ground and O2S connector terminals No. 2 and No. 4. If continuity does not exist on either circuit, repair wiring harness as necessary. If continuity exists and preceding test procedure did not discover any trouble codes, replace O2S.
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