the check light stays on. Had diagnostic test at GM garage, it coded PO 171 and PO 172; meaning leaking head gaskets and leaking intake manifold. Car never has overheated and have added very little antifreeze. Two other tests run and they both coded PO 171 and PO 174.Noticeable surge with small miss at idle speed.Have 94,000 miles,would like to keep. Any help would be appreciated.
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2001 Cadillac DeVille DTS Question: onstar engine problem
Answer #1Jim Taddei February 07, 2011, 16:57Master
Codes P0171 and P0174 on your 2001 Cadillac Deville are for a lean running engine. While this commonly indicates an engine vacuum leak, that does automatically mean head gaskets or intake manifold. One common case of a vacuum leak on this engine would be the seal between the intake manifold and the throttle body. Please review this RepairPal article for more information on these fault codes - http://repairpal.com/OBD-II-Code-P0171-and-P0174