LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2002 >> XL-7 Plus >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0401 Or DTC P0402 >> Diagnosis & Repair Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair Procedure

  1. If engine system check has been performed, go to next step. If engine system check has not been performed, go to A4: ENGINE SYSTEM CHECK  under SYSTEM TESTS.
  2. If DTC P0403 is also set, perform testing for DTC P0403 before proceeding with this test. See DTC P0403 . If DTC P0403 is not set, go to next step.
  3. If scan tool is not available, go to next step. Start engine and allow it to reach normal operating temperature. Using scan tool, select MISC TEST mode and open EGR valve. As EGR valve opens, engine idle speed should decrease. If EGR valve operates as specified, go to next step. If EGR valve does not operate as specified, go to step  5.
  4. Check MAP sensor operation. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If problem is found, repair or replace MAP sensor as necessary. After repair, repeat DTC CONFIRMATION TEST . If MAP sensor tests okay, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If intermittent problem is not found, substitute a known good ECM and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  5. Turn ignition off. Disconnect EGR valve 6-pin harness connector. EGR valve is located on intake manifold. Turn ignition on. Measure voltage between ground and EGR valve harness connector terminal No. 2 (Blue/Black wire) and No. 5 (Blue/Black wire), individually. See Fig 1. If 10-14 volts are present at both terminals, reconnect EGR valve harness connector and go to step  7. If 10-14 volts are not present at both terminals, go to next step.
  6. Repair open or short in Blue/Black wire between EGR valve and main relay. See WIRING DIAGRAMS article. After repair, repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  7. Turn ignition off. Disconnect ECM 26-pin harness connector C51-3 and ECM 30-pin harness connector C51-2. ECM is located under instrument panel, behind glove box. See Figure. Measure resistance between ECM harness connector terminal No. 4 (Blue/Black wire) and ECM harness connector C51-2 terminals as follows:
    • No. 12 (Light Green/Red wire).
    • No. 13 (Light Green/Yellow wire).
    • No. 14 (Light Green/White wire).
    • No. 15 (Light Green wire).
    Resistance at each terminal should be 20-24 ohms at 68°F (20°C). If resistance is as specified, go to step  9. If resistance is not as specified at any terminal, go to next step.
  8. Check for and repair open or short in circuits between ECM and EGR valve. See WIRING DIAGRAMS article. If no problem with wiring is found, replace EGR valve. After repair, repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  9. Check MAP sensor operation. See MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If problem is found, repair or replace MAP sensor as necessary. After repair, repeat DTC CONFIRMATION TEST . If MAP sensor is okay, go to next step.
    10. NOTE: DO NOT use a sharp tool to remove carbon. Be careful not to bend or score EGR valve or rod, or damage valve seat.
  10. Check for plugged EGR valve passage. If EGR valve passages are okay, check EGR valve operation. See EXHAUST GAS RECIRCULATION under EMISSIONS SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. If problem is found, repair or replace as necessary. After repair, repeat DTC CONFIRMATION TEST . If EGR valve operation is okay, problem is probably intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. If intermittent problem is not found, substitute a known good ECM and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
Fig 1: Identifying EGR Valve Harness Connector Terminals
G00163649Courtesy of SUZUKI OF AMERICA CORP.
scientia non olet · About LEMON Manuals