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I have a 94 Dodge Shadow ES. The O2 sensor went out last April. I got it replaced and now it is giving me another 51 code and my gas mileage went from 30MPG to @ 21MPG. Is there something that could cause the sensor to go bad so soon? I'm going to replace it again but don't want to have to do this every 5 to 6 months. What are the things I should consider that can cause premature failure?
 

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it could be that your computer on the vehicle is messing up. just a thought
 

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Discussion Starter #3 (Edited)
Thanks for the though of the computer, but I'm going to see if the sensor is still under warranty and replace it. Then I'll see how long it will last. I now have another problem with this car. The accelerator sticks sometimes. It is not the cable or the return springs. It is like the throttle body butterfly will stick when the engine gets warmed up. I have sprayed it ( on the out side of the TB) but to no avail. Tomorrow I'm going to get some Injector/carburetor spray and clean the TB.
 

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you should also watch out for a faulty catalytic converter. when the O2 sensors go bad, the car runs a default rich fuel map. this will drastically over work the cat, making it get rid of excess unburned hydrocarbons and can burn up the catalyst or plug the catalyst matrix (basically a honey comb type deal). if the cat goes due to an O2 sensor and the senor is replaced, but not the cat, it can cause all sorts of things to go wonky in you emissions system. good luck.
p.s. computers rarely go bad on their own. they usually have "help" from mechanics not disconnecting batteries or from bad grounds or water immersion.
 

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o2 sensor

grreed247 said:
I have a 94 Dodge Shadow ES. The O2 sensor went out last April. I got it replaced and now it is giving me another 51 code and my gas mileage went from 30MPG to @ 21MPG. Is there something that could cause the sensor to go bad so soon? I'm going to replace it again but don't want to have to do this every 5 to 6 months. What are the things I should consider that can cause premature failure?
Only a guess, the o2 sensor goes bad and the system goes to open loop. I have heard that using sealer of the wrong type can result in a o2 sensor going bad. I don't remember what is in the sealer but when you buy sealer it needs to say sensor safe. Remember when leaded gas would trash out a sensor. If you pull it off and I have seen this take a torch and de slag the unit. That was many years ago. The o2 senor was tested with a multimeter, Hey maby the guy that did that got luck. I don't know if your engine is using oil, seems like a long time ago I read that there is a tiny hole in senor that has to see the 02 and if it is plugged? Sorry I can not be more helpful. Jim
 

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An O2 Sensor is nothing more than an elctrochemical battery it reads a parameter of no more than .001-.75 volts usually no more than that. As the exhaust flows through the system it "sees" the amount of fuel being burned. If the system is rich it will produce more voltage, less if it's lean. I would switch gas stations first then get a quality Bosch replacement at NAPA. They are a simple device and rarely go bad, it's more of the contaminants in the fuel or wrong fuel that coats the tip and then the sensor cant get the reading. Hope this helps.
 
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