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Home >> Cadillac >> 1991 >> Seville Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> Pcm Code EO48, EGR System Fault (1 Of 2) >> Vacuum Test

Vacuum Test

  1. Connect vacuum gauge to source side of EGR solenoid. Start engine. Manifold vacuum should be present. If not, repair leaks or obstruction between EGR solenoid and throttle body.
  2. Connect vacuum gauge to EGR valve vacuum supply hose. There should be no vacuum with engine at idle. If vacuum is present, go to PCM CODE EO48 (2 OF 2).
  3. With gauge attached to EGR valve vacuum supply hose, disconnect EGR solenoid connector. With engine at idle, vacuum reading should be greater than 8 in. Hg. If not, repair leak or obstruction in EGR valve vacuum hose.
Fig 1: PCM Code EO48, Schematic, EGR System Fault
G91D09356
Fig 2: Flow Chart 1 Of 2, PCM Code EO48, EGR System Fault
GB0022543
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