: SES Light - codes P0171 & P0174 - 2004 Seville



gbrown2934
12-03-12, 02:06 PM
Have a 2004 Seville with the SES light on referred to codes mass air flow sensor lean bank 1 and 2. Replaced Mass Air Flow sensor - light still comes on, any other suggestions. Thanks

Submariner409
12-03-12, 04:39 PM
Yes. The MAF was not your problem in the first place. P 0171 / P 0174 refer to fuel trim system, lean mixture, Bank 1 & 2. Usually caused by severe vacuum leak, in your case by a crack in the bottom of the bellows on the "plenum", that rubber/metal connector between the throttlebody and intake manifold.

The fuel rail and intake manifold must be removed and a new plenum assembly installed. Many pictures, parts, and diagrams of all this in my albums; click my username, open the profile - left column, 2 albums, 6 pages of your car and parts.

This thread belongs in either Seville or Northstar Performance: It has nothing to do with electrical systems. Better response in Engines: Northstar Performance. Off we go. (Yes, there are other threads in Electrical that don't belong there - we'll get to them)

gbrown2934
12-17-12, 01:43 PM
Thanks Submariner409, had my friend do the work, didnt even have to remove fuel rails, found the plenum boot large split, wasted $$$$$$$$$$$ on 2 Mas air flow sensors and a egr valve, car runs great, so far ""NO"" SES LIGHT.

subzero32
12-20-12, 10:24 AM
I have the same 2 codes. I'll have to check out the plenum.

subzero32
12-22-12, 11:34 AM
So I checked out all my vacuums hoses and there was a small crack off the intake piping that goes to the PCV. I put some electrical tape as a temp fix until i can buy new tubing, cleared the CEL codes and 320 miles driving and it still has not thrown the code. I really did not want to replace the plenum Behring the throttle body. Hope this was the issue.

----------

So now 15 min later the CEL is back on. The search continues for the leak.

Ranger
12-22-12, 03:45 PM
With those two codes, my money is on the plenum.

subzero32
12-22-12, 06:09 PM
How hard is the plenum to replace? Seems pretty straight forward.

----------

Anyone have the part #?

Submariner409
12-22-12, 06:59 PM
Look in my albums. It's all in them. Click the Comunity tab; the red Seville - 2 albums, 6 pages of Northstar stuff.

Google something like "cadillac forums northstar plenum replacement." Also, try down in Discussions, Cadillac Tech Tips.

It's all in these forums a hundred times.

Now that the OP's thread has been hijacked, is the 2004 SRX drivetrain identical to his 2004 FWD Seville ?? If not, all bets are off.

subzero32
12-22-12, 07:21 PM
My SRX is V8 AWD. Are all bets off for the plenum?

Ranger
12-22-12, 09:03 PM
No, it's still the plenum. Only difference is yours is a north/south mounted engine (the way God intended) as opposed to a sidewinder.

subzero32
12-23-12, 08:15 AM
No, it's still the plenum. Only difference is yours is a north/south mounted engine (the way God intended) as opposed to a sidewinder.

Lol. I agree 100%