LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Acura >> 1991 >> Legend Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Code 43, Code 44: Fuel Supply System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Code 43, Code 44: Fuel Supply System

NOTE: For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section. For vacuum diagrams, see VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section.
  1. Turn ignition off. Remove ACG fuse in underdash fuse box for 10 seconds to reset ECU. Start engine, and allow cooling fan to come on. Hold engine at 3000 RPM for 2 minutes. Connect jumper wire to diagnostic connector. Observe CHECK ENGINE light. If light does not flash, problem is intermittent.
  2. Check for poor or loose connections at left O2 sensor (Code 43) or right O2 sensor (Code 44), ECU and connectors C355, C354 and C356 at right shock tower.
  3. If CHECK ENGINE light is flashing Code 43 and/or 44, turn ignition off. If driveability problems are also present, test fuel related components. See SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE Section. Repair as necessary.
  4. Disconnect ECU connector. Connect ECU test harness between harness connector and ECU. See Figure . Turn ignition off, and wait at least 2 minutes.
  5. If Code 43 is present, install a jumper wire between terminals A10 and A26. Attach a digital voltmeter to terminal D14. Turn ignition on. Voltage should be .4-.5 volt, and then drop to below .1 volt within 2 minutes.
  6. If O2 sensor does not respond as described, go to next step. If voltage changes as described, substitute a known good ECU, and retest system. If problem goes away, replace ECU.
  7. Ensure White wire between ECU terminal D14 and O2 sensor terminal "B" has good continuity. See Figure . If wire is okay, replace O2 sensor.
  8. If Code 44 is present, install a jumper wire between terminals A12 and A26. Attach a digital voltmeter to terminal D16. Turn ignition on. Voltage should be .4-.5 volt, and then drop to below .1 volt within 2 minutes.
  9. If O2 sensor does not respond as described, go to next step. If voltage changes as described, substitute a known good ECU, and retest system. If problem goes away, replace ECU.
  10. Ensure Red/Blue wire between ECU terminal D16 and O[I2] sensor terminal "B" has good continuity. If wire is okay, replace O2 sensor.
scientia non olet · About LEMON Manuals