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So I just replace my Cat. Converter with all new sensors in them. I just replaced my spark plugs. (I'm knocking out these check engine light problems) and I think I'm getting close to the root as to why these other parts went bad.
Can anyone tell me why my o2 sensor would be stuck on "lean"
Yeah the truck seems to "miss" here and there but it runs and idles great 95% of the time. I'm not sure if it's a "miss" or a fuel injection issue. But the code p2195 has me thinking it's something in the vaccum or fuel system. The code says the o2 sensor is stuck on Lean .. Should I focus more on a fuel issue or an exaust/vaccum issue ? I'm just ready to have this thing fixed. I believe the previous owner let it run like this for a while thus ruining the cat converters, sensors, and spark plugs. I have now replaced all of these things and each time I fix something a new code pops up and the current code is p2195 I'd like to get this issue fixed as not to harm the cats and sensors I just bough (Motorcraft and oem cat converter.. no cheap to say the least 20$ a piece for spark plugs !
I know this post is a couple months old but if you havnt yet resolved your issue I have some info for ya. P2195 is NOT usually a bad o2 sensor. You are absolutly on the right track with thinking it has to do with fuel/vacuum issues. This is almost always the case. Just yesterday I was working on an 03 4.6l expedition with multiple o2 sensor codes including p2195 which would occasionally start to shake a little at idle. I was totally stuck on a fuel delivery problem and since it was only pulling lean on bank 1 I rulled out fuel pump/filter. Also most (not all) vacuum leaks will pull bank 1 and 2 unless its in the intake manifold effecting individual cylinders. My issue turned out to be a fuel injector going out. I diagnosed this issue by unplugging the electrical to each injector one at a time and testing the actual injector's resistance with my digital voltmeter. All the injectors were reading at between 16.2 and 16.8 except for one which was 14.4. With a bad coil an injector cannot produce the proper spray. Now if its not a bad coil (bad resistance) it can be clogged. Most people use injector cleaner but my mechanic genius friend swears by (and has used many many times) 1 quart of ATF (I know it seems crazy) in the gas tank with at least 15 gallons of gas, and yes its perfectly safe for your entire fuel system as long as its diluted enough. If its not an injector it could also be a dirty mass air flow sensor which can just easily be cleaned with maf sensor cleaner or electronics cleaner, nothing else. If you think your maf is not working you can always use your trusty digital voltmeter to check that as well. If neither of those are the culprit than just spay the engine down on all the vacuum lines and intake manifold with carb cleaner and listen for the rpms to rev to possibly find a vacuum leak. There are a couple other possiblities but these are the most common. Yes an exhaust leak would pull that code as well but you should be able to hear that pretty easy. Hope this helps.
ps, after changing anything if you dont want to wait till a code pops up to see if you fixed it you can always climb under the car and manually check the o2 sensor readings with a digital voltmeter while the vehicle is running and is warmed up. On most o2 sensors that have 4 wires, you test the black one. The gray wire is ground and the 2 white wires are to heat the sensor. Make sure your black probe on the voltmeter is grounded to something like your frame. Proper upstream (pre-cat) readings should constantly fluctuate widely between .1 and .9, lean will fluctuate only in the .1-.3 range and rich will stay in the .7 - .9 range. Again this does not mean you have a bad sensor.
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