LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 1995 >> ES 300 >> Repair and Diagnosis >> External Pages >> Different car >> Section 12 (Engine Controls - Tests W/Codes - OBD-II) >> Diagnostic Testing >> Code P0401: Insufficient Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (Using Lexus Scan Tester)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair (Using Lexus Scan Tester)

WARNING: This page is about a different car, the 1995 Lexus LS 400. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect Lexus scan tester to DLC No. 3. Turn ignition on. Read EGR gas temperature. Temperature should be 50°F (10°C). If temperature is as specified, go to step 5). If temperature is not as specified, go to next step. If temperature displayed is 37.6°F (3.1°C), locate and repair open circuit in EGR gas temperature sensor circuit.
  2. Disconnect EGR gas temperature sensor harness connector. Connect jumper wire between harness connector terminals. EGR gas temperature displayed should be 318.7°F (159.3°C). If temperature displayed is not as specified, go to next step. If temperature displayed is as specified, inspect sensor connectors and terminals. Repair as necessary. If connectors are okay, replace sensor and retest.
  3. Remove jumper wire. Turn ignition off. Access ECM behind glove box. Connect jumper wire between ECM harness connector terminals No. 2 (Red/Green wire) at ECM E12 connector and No. 22 (Brown wire) at ECM E13 connector. See Figure. Turn ignition on. EGR gas temperature displayed should be 318.7°F (159.3°C).
  4. If temperature displayed is as specified, locate and repair open in circuits between ECM and EGR gas temperature sensor. If temperature displayed is not as specified, replace ECM and retest.
  5. Check EGR valve. See SYSTEM/COMPONENT TESTS . Replace as EGR valve as necessary. If EGR valve is okay, replace ECM and retest.
scientia non olet · About LEMON Manuals