96 sedandeville 4.6

1996 CADILLAC DEVILLE
106,000 MILES • V8 • FWD • AUTOMATIC
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BROSCOFATZ101
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  • 1 POST
My service emission system is diplaing on dash engine light on trouble codes are p0171 & p0174 car Manuel definition is fuel trim system lean (bank 1) for both codes need help any sugestions on were to start pleas& thanks..describe your problem.mpix@match.com
Feb 5, 2011 at 11:28 AM
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JACOBANDNICKOLAS
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The first thing to check for is a vacuum leak. The trouble codes are for both bank 1 and 2. That tells me it isn't one specific part for one bank. Check around the intake, vacuum hoses... Here are a list of items that should be checked:

Air induction system
PCV hose connection
PCV hose
Injector blockage (would only cause one of the codes)
Mass air flow meter
Engine coolant temp. sensor
Fuel pressure (directions on our homepage under DIY)
Fuel leak
ECM
Feb 6, 2011 at 1:05 AM