LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 1994 >> LS 400 >> Repair and Diagnosis >> Engine Performance >> Emissions >> EGR Function Testing - LEXUS >> EGR Function Testing - LEXUS >> Test 4 >> EGR Vacuum Modulator Check
April 5, 2026: LEMON Manuals is launched! Read the announcement.

EGR Vacuum Modulator Check

  1. Turn engine off. Label and disconnect all vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" with finger (twin ports on side of modulator). Blow air into port "Q" (single port on side of modulator). Air should flow freely out of filter.
  2. Start and run engine at 3500 RPM (ES250 and ES300) or 2500 RPM (GS300 and LS400). Block ports "P" and "R" with finger. Blow air into port "Q". Air should not flow out of filter. If air flows out of filter, replace EGR vacuum modulator.
scientia non olet · About LEMON Manuals