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Oct 17, 2003 | 09:49 PM

dweave

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Joined: Aug 2002

Posts: 10

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From: San Jose USA

Codes

Hello all, I hope someone out there can help me. I have a 96 Bronco with a 351 and the check engine lite keeps coming on. For a while it was only once in awhile (intermittent you might say) now it comes on all the time even when I erase the codes. I have a Digital OBDII code reader. The codes I am getting are: P0171 System to Lean (Bank 1) and P0133 02 Sensor Circuit Slow Response (Bank 1 Sensor 1). I have changed all the sensors (3) and one of the Cats (the one before the muffler, I have 2 Cats). I have 3 1/2" single exhaust. Can someone please tell me where to start looking so I can fix this problem, or do I have to take it to the dealer? Any help would be appreciated. If you can, could you please also e-mail me at: dweave@pacbell.net or dcweave@msn.com

Thank you so much for your time

Don

Oct 13, 2008 | 12:00 PM

jb40thpony

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Joined: Oct 2008

Posts: 1

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I had the same thing happen with a '04 mustang gt I had. But it was becuase i put after market off-road headers and x-pipe. I had to buy mil-simulators to keep from getting the check engine light. If you have already replaced all the o2 sensers and the cats there should'nt be, in mind atleast anything to cause the "idiot light" to come on.. I've got a '95 bronco, but its not odb2 so im not sure if yours has a maf and a egr sensor like my mustang did or not. I'f it does, i would check those out cause i think they work in unision with the o2 sensors. Easy way to re-set them is to disconnect the -side of the battery and turn the ignition key on for about 30 sec to a min. That will clear out the codes, but if there is a fault they will come back. So my advice would be to just buy some mil-simulators and don't worry about it.

Oct 20, 2008 | 04:15 PM

greystreak92

Lead Driver

Joined: Sep 2002

Posts: 9,182

Likes: 12

From: Gateway to the West

Getting those codes indicates that only one of the O2 sensors (bank 1) is getting erroneous readings. This can be caused by something as simple as a leaking exhaust gasket at the manifold. My suggestion, if you have replaced the O2 sensors would be to make certain you have no exhaust leaks in the left bank of cylinders and then check the wiring to that sensor for damage. Since you are getting the same codes even after replacing the sensors its highly unlikely that the sensors are the issue.