Help! P0174 :(

MY 04 GT · Jun 11, 2010

Ok, well this is my first post on the forums. Sad to say this first post is about an issue that my car is enduring.

I have a short ram intake from american muscle. the 55 dollar one. There are no vacuum leaks. Nothing. I Installed the Intake, all is well. No check engine like. Drove the car for about a month and then got my pypes 409 OFF ROAD x pipe installed. I have MIL eliminators on the car. I still had a check engine light. I got a tune from BAMA at american muscle for my sct tuner to turn the cel off. It worked for about 30 miles and the light came on again. I scanned the codes and i got a p0174. running lean in bank 2... drivers side. if nothing happened during the intake install, then it must be the x pipe install right?

At the moment, the car still has the MIL eliminators plugged in on the rear 02 sensors. could this give me the code? or is this something that has to do with the front 02 sensors? Am I totaly off the money? please help me if you have any ideas of what could be throwing this p0174 check engine light code.

thanks for your time.

Shiroelex · Jun 11, 2010

I've still got my MIL eliminators spliced into my rear O2s, along with my custom Xcal3 tune with the rears disabled. I've never gotten a light for the rear oxygen sensors, even before the tune. If it were a problem with them, the code would read something like Oxygen Sensor Malfunction Bank 1 (or 2) Sensor 2. Either that, or Catalyst Efficiency Below Threshold.

For your lean code, I would try cleaning your MAF first, double check all of your vacuum connections, then try changing out the upstream oxygen sensor on that side. I'd even throw in a little bottle of Lucas fuel treatment, and some Seafoam through the intake.

I ended up with a lean code once when the hose that connected to the front of my plenum slipped off a bit (The one that runs to the passenger valve cover). My aftermarket plenum had a smaller sized barb fitting on it than the stock hose was, so I had to make an adapter for it.

wmburns · Jun 11, 2010

Check the EGR tube for exhaust leaks. Also check the vacuum lines to/from the EGR DPFE sensor. These are hard to see because they are so close to the firewall. The exhaust gas will make them hard and brittle.

Any air entering via an exhaust leak will make the O2 sensor THINK it is lean.

OBTW, the P0174 is associated with the Front O2 sensor. The MIL's are for the rear's.

FEARNO1 · Jun 11, 2010

I had that same code and my problem was an exhaust leak at the manifold x-pipe connection. Fixed the leak and the code went away

MY 04 GT · Jun 11, 2010

FEARNO1 said:
I had that same code and my problem was an exhaust leak at the manifold x-pipe connection. Fixed the leak and the code went away

okay thanks! and i know i was just saying that the mils were on the rear because i thought i may make a difference.

thanks for all the help guys!

nyuk98gt · Jun 11, 2010

MY 04 GT:

"FEARNO1" nailed it: a leak (even a tiny one) is going to allow air in and the extra O2 is going to make the PCM think the engine is running lean.

Loosen the joints on the intermediate pipe (don't take the bolts out, just get them loose so that the pipe can be adjusted). Put a floor jack under the pipe and get the pipe nice and level with the bottom of the car. Snug up the joints: tighten one side a bit, then the other so that the joint is pulled together evenly. When you are torquing the bolts to spec, keep going side-to-side until the desired torque is achieved. Do the front joints first and then the catback/intermediate pipe joints.

If you want to use copper (O2-friendly), high temperature RTV on each joint, you can use it with confidence. It is not essential but it's an option. You would have to disconnect the o/r pipe completely so you can put a nice bead of RTV where it needs to go.

HTH,

Chris

p.s.--Welcome to StangNet!

Help! P0174 :(

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