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Ron Z.
Ron Z., - Buick Tech -
Category: Buick
Satisfied Customers: 17782
Experience:  18+yrs experience. State Inspector and Buick Diagnostics
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Buick Century: Where is the O2 sensor heater fuse located for

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Where is the O2 sensor heater fuse located for a Buick 2002 Century?
Welcome! I'm Ron Z! Make sure to use Reply if needed! And PLEASE remember to RATE my answer at the end!

The fuse for the Oxygen Sensor heater is located in the underhood fuse block. It's fuse #29 (see image below). It should be labeled as "OXY SEN". If the fuse is good, make sure you have the correct Oxygen Sensor installed (OEM P/N: 12559850). If these all check ok, you will need to inspect the electrical connector and wire harness for any loose, broken or rubbed through wires that may be touching metal at some point.
Customer: replied 3 years ago.

You are gonna love this, but I am trying to feed a leaner signal with the Innovate LC-1 wideband sensor, but had to hook up the heater section of the old sensor dangling in the open in the engine component to keep the P0135 signal away. Running HHO trying to get better mileage. Its resistance seems to be one half the normal amount after a few months. (got wet?) I haven't checked the fuse yet but just in case, any possibility the PCM circuit got damaged? If so, would any similar GM model V6 same vintage PCM work without reprogramming?

Yikes. Uhm. Probably a bit out of my league here, but... I'm going to say that the heater section of the old sensor "dangling" there isn't going to solve anything. If it DID get wet, then there's a chance hat maybe the PCM did take some damage. When replacing the PCM it needs to be the same numbers (when removed there's a sticker on top) and then will need to be re-programmed (no way around the programming, it needs to be done). At this point, if the fuse is good, go back to an original O2 sensor. If the problem persists, more than likely the problem is in the wiring or the PCM. If a new, original O2 solves the problem, try a more "efficient" way to improve fuel economy, like the "G-Force" chip. I think leaving that heater "dangling" is what got you into all this.
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