Code 48: Air By-Pass Valve

NOTE: Use continuity test guide for symbol reference. See Figure .

Check base idle speed. See appropriate ON-VEHICLE ADJUSTMENTS article in ENGINE PERFORMANCE. Test air by-pass valve, see Fig 1 . See appropriate WIRING DIAGRAMS article. Test road speed sensor input, see Fig 2 . After completing the tests, retest the vehicle to ensure the faults have been rectified. If faults still persist, recheck using Lucas Diagnostic Equipment or Test Book.

Fig 1: Air By-Pass Valve (Test Procedures No. 15 & 16)

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Fig 2: Road Speed Sensor Input (Test Procedure No. 25)

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