LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Acura >> 1993 >> Legend Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Trouble Codes >> Code 43 Or 44: Fuel Supply System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Code 43 Or 44: Fuel Supply System

  1. If referred here from CODE 1, go to step 2. Turn ignition off. Remove ACG fuse (No. 15, 7.5-amp) from underdash fuse box for 10 seconds to reset ECM. Warm engine until cooling fan comes on. With transmission in Neutral, hold engine speed at 3000 RPM for 2 minutes. Check ECM for fault codes. If Code 43 or 44 is present, go to next step. If Code 43 or 44 is not present, problem is intermittent. Check for poor connections at ECM, HO2S and wiring harness connectors. Test drive vehicle and retest.
    NOTE: If driveability problems are present, test fuel-related components. See SYSTEM/COMPONENT TESTS article in this section.
  2. Turn ignition off for at least 2 minutes. Connect ECM Test Harness (07LAJ-PT3010A ) between ECM and ECM harness connectors. See Figure .
  3. If Code 43 is present, install a jumper wire between test terminals A10 and A26. Attach a digital voltmeter to test terminals A26 (-) and D14 (+). If Code 44 is present, install a jumper wire between test terminals A12 and A26. Attach a digital voltmeter to test terminalsA26 (-) and D16 (+). Turn ignition on.
  4. Voltage should be .6-.8 volt when ignition is turned on, then drop to less than 0.1 volt within 2 minutes. If voltage is correct, go to step 6. If voltage is not correct, disconnect HO2S connector. Measure voltage between HO2S wiring harness connector terminals "A" (+) and "B" (-). See Figure .
  5. If more than 0.1 volt is present, reconnect HO2S electrical connector. Warm engine until cooling fan comes on. With transmission in Neutral, raise engine speed to 3000 RPM and hold for 2 minutes. Measure voltage between test harness terminals D14 (+) or D16 (+) and A26 (-). Voltage should be more than 0.5 volt at wide open throttle and less than 0.5 volt when throttle is quickly released. If voltage is as specified, test fuel-related components. See SYSTEM/COMPONENT TESTS article in this section. If voltage is not as specified, replace HO2S.
  6. If voltage was correct in step 4, disconnect HO2S connector. Measure voltage between test terminal D14 (left sensor) or D16 (right sensor) and A26. If more than 0.1 volt is present, replace HO2S. If voltage is 0.1 volt or less, disconnect connector "D" from vehicle wiring harness.
  7. Measure voltage between test terminals D14 (+) or D16 (+) and A26 (-). If more than one volt is present, repair short in Red/Blue wire (right sensor) or White wire (left sensor) between HO2S and ECM connector. If voltage is one volt or less, replace ECM and retest.
scientia non olet · About LEMON Manuals