2005 Buick Lesabre Not Passing Emissions. Help or Ideas needed.

[10thmountain]

EGR valve needs replace or clean...possible fuel pressure issue and or dirty injectors....1/4 tank of 93 and a entire bottle of 104 octane booster..but possible that the PCV valve is on that side may be the problem too..check vacuum hoses to the booster and the vac rail at idle with soapy water and spray bottle..you will find it when the idle raises a bit

Good Idea on the 93 and octane booster, PCV valve is EASY to replace.

 

[potenza]

sounds like its sucking air somewhere, the gaskets on the intake fail. BUT have it diagnosed by a pro or throw parts at it, then pay a pro to fix it. OR replace all the parts folks on here say they fixed their sisters boyfriends car years ago.

 

[brad sweet]

Good Idea on the 93 and octane booster, PCV valve is EASY to replace.

if it has high miles cleaning around the throttle blades on the intake and misting some water down the intake while running (ahead the MAF sensor) will break up some carbon deposits on the valves and pistons..but the octane boost is about 85 % kerosene (petroleum distillates and benzine) and will help remove deposits..do this before you replace the O2 sensor

 

[10thmountain]

I think the 02 Is the issue the upstream one.

 

[brad sweet]

also the coolant temp sensor has alot to do with the fuel curve on ECM..its possible it is low on anti freeze or sensor is out of range

 

[10thmountain]

also the coolant temp sensor has alot to do with the fuel curve on ECM..its possible it is low on anti freeze or sensor is out of range

That was another code I found today .....So much fun...

 

[brad sweet]

That was another code I found today .....So much fun...

check the level and test the sensor it may be your only problem..very common problem cheap fix but usually expensive to find after all other parts are replaced.. or radiator cap not holding pressure and sending the sensor wrong

 

[harrycalahan]

Not sure if your model had it but they ran plastic intake plenums on the 3.8 and they would crack or leak at the gasket. Need to get it smoked to see if it (or other items) are leaking.

 

[Greybeard]

First down stream o2 sensor. Bosch would be good, don't splice replace with connector installed on o2sensor. Reset Ecm and all should be good

 

[nitrousfedlx]

I think the 02 Is the issue the upstream one.

This is what I am thinking too. P0170 and P0171 r 2 dtc codes that ur usually H02S (upstream) as opposed to catalyst monitors (downstream) after the cat. I think 1 is bank one and the other is bank 2 if memory serves me correct. LOL