Question about Chevrolet Camaro

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I have a 2002 Z28 Camaro that I am currently trying to get to pass emissions inspection. I have just replace both upstream O2 sensors, and I am still getting a P1133 code. I cant figure out the problem, any ideas?

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  • mst1969 Apr 16, 2009

    I have ****** Long Tube headers, and a full exhaust system, but if the headers are causing this problem, then why would it not be happening on the driver side O2 as well?

  • mst1969 Apr 16, 2009

    when I changed them, i didnt alter the wires off the 02 sensors I put in. The previous owner had just cut and spliced the old wires before, so when I changed them out, I took the old connector, and found the opposite end connector, and made my own extensions.

    After the extensions were down, they all showed good continuity in all 4 wires. Would the computer be able to eventually compensate for the length of wire?

  • Dave  C
    Dave C May 11, 2010

    Aah, good call blueextc, it's always the after market garbage that causes problems. Chances are, you have a leak at the header flange or coupling, anything where air can get in ahead of the sensor.

  • Dave  C
    Dave C May 11, 2010

    The code indicates that the mixture is not fluctuating between lean and rich like it should on bank one (drivers side). You need to check the car at idle and then drive the car at a steady speed and monitor bank 1 with a scan tool and see if that sensor is indicating continuously rich (>.5V) or continuously lean (<.5V) You probably have a vacuum leak that is causing the sensor to always be at one end, but it could also be a fuel problem of some sort that is causing over-fuelling. Find out which, first and go from there.



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P1133 - Insufficient Switching on a Pre-Cat sensor, Bank 1 Sensor 1
Is the exhaust stock? or do you have long tube headers?? The long tube headers cause the heat-up time on the o2s to be longer (causing the switch time to take longer (p0133/p0155)).

Otherwise - insufficient switching of the o2...exhaust leak possibly near the sensor... sometimes a blown head gasket can cause this code too.

Thanks for using FixYa - a FixYa rating is appreciated for taking the time to answer your FREE question.

Posted on Apr 16, 2009

  • blueextc3221
    blueextc3221 Apr 16, 2009

    Some people with LT headers swear by Denso sensors - however it is my experience that iIt's not about the brand of O2 sensor but the fact that the sensors don't work so well in long tube headers.

    Did you use real O2 extensions or cut and splice yout O2 sensor wires? It has been my experience also that cut and spliced O2 sensor wires always seem to cause problems.

    If an O2 cable is cut, spliced or the pigtail connector is taped or sealed it may no longer function reliably. O2 sensors require clean outside air to compare with the exhaust mixture. This clean air is provided from the pigtail connector thru a very small gap in the wires insulation to the sensor. Therefore altering the pigtail can block or disrupt the outside air flow to the sensor.

    The long tube headers cause the heat-up time on the o2s to be longer (causing the switch time to take longer (p0133/p0155)

    You stated you just changed them - it will take a few heat/cool cycles for the code to go away... and i would venture a guess that there is an improper length on the wire to the one side - and the computer isnt liking the change in stats.

    Thanks for using Fixya!!

  • blueextc3221
    blueextc3221 Apr 16, 2009

    i would guess the problem lies with the wiring - not the sensor.

    computer would not compensate for a longer wire or delay in signal coming back.

    A CANDI II module may be able to reprogram it - however unless you know someone with the tool - it is quite expensive.



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