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  1. Help Please: 99 Suburban K1500 LT 5.7 fresh rebuild P0134 P0154 Open Loop

    Chevy Suburban Forum (GMC Yukon XL)
    Please Please Help.. 1999 Suburban K1500 LT 5.7 Vortec with the newer Spider style. Completely Stock other than added a second battery with a relay. Background: Fresh Rebuild after previous head gasket and 2 cracked heads. Issue: P0134 P0154 and seem to be in Open Loop all the time...