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My 99 Legacy Brighton Wagon 2.2L EJ22(California Emissions) CEL code P1133. It is translated to HO2S High input circut fault. I have chaged out the part (the oxegen sensor) twice, the code will not clear out. The Volts should fluctuate roughly .05 - 1.0v, usually les than 1.0v i.e; .65-.95v. at any rate, the my live data scanner shows the volt reading as 3.764v! This is the up-stream ho2s. (pre-cat) The down stream ho2s reads a normal input of .66-.88v respectively. The first sensor replacment was a cheapo universal the pcm would not recognize/read the new sensor. The second sensor was used from another 99(CA EM) Same thing P1133 high output. I am kinda stuck here. Not sure how to proceed. Could it be the connector wires from the sensor plug to the PCM? Any TSB or MODIS (snap-on's scanner) troubleshooting say that Tech's in the field report that 9 times out of t10 the sensor is failing and not the PCM or anything in between. Has any one ever encountered this or something similar before? Any Ideas?

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The P1133 code is for a problem in the heater circuit of the O2 sensor. If the ECU/PCM ''thinks'' it can't control the heater properly, it will set the code. The high voltage you measured for the sensing element is apparently not a concern, as others have reported proper operation as long as the O2 sensor/heater and wiring are good. Although not specific to your model/year, see the following threads for further insight:

http://www.ultimatesubaru.org/forum/showthread.php?t=66744

http://www.ultimatesubaru.org/forum/showthread.php?t=98800

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