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Home >> Acura >> 1990 >> Integra LS, 2D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Code 43: Fuel Supply System
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Code 43: Fuel Supply System

NOTE: For wiring diagrams, see WIRING DIAGRAMS article. For vacuum diagrams, see VACUUM DIAGRAMS article.
  1. Turn ignition off. Remove hazard fuse in main 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. Observe CHECK ENGINE and LED lights. If lights are not on, problem is intermittent.
  2. Check for poor or loose connections at oxygen sensor and round connector C216 at right shock tower. If CHECK ENGINE light is on and LED indicates Code 43, inspect fuel pressure regulator. See BASIC TESTING . Replace as necessary.
    NOTE: Per Acura Service News number ASN 0390-03 oxygen sensor connector should not be disconnected at this point. Backprobe the connector to obtain voltages during this test.
  3. If fuel regulator is okay, with engine running, measure voltage between oxygen sensor and ground. Voltage should be above .6 volts at wide open throttle up to 4500 RPM. When throttle is quickly released voltage should be .4 volts.
  4. If voltage is not correct, replace oxygen sensor. If voltage is correct, stop engine. Reconnect oxygen sensor connector. Connect ECU test harness to ECU. Restart engine and warm to normal operating temperature. Measure voltage between C16 and A18.
  5. Voltage should be the same as in step 3). If voltage is not correct, repair open or short in White wire between C16 and oxygen sensor. If voltage is correct, substitute a known good ECU and recheck. If problem goes away, replace original ECU.
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