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Home >> GMC >> 1990 >> Forward Control 3.9 L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - TBI >> Diagnostic Tests >> Code 45: Rich Exhaust Indication >> Fuel Pressure High

Fuel Pressure High

If fuel pressure is too high, air/fuel ratio will be rich. For fuel pressure checking procedure, see BASIC TESTING article. The ECM can compensate for slight increases but if air/fuel ratio becomes too rich a Code 45 will be set.