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toyota avalon 2000 xls check vsc vsc off lights on with code p0171

I bought my current car by this Jan. This is my first car. When it did the inspection, the car changed the new battary. but 2 months later, the car can't be started, the car was towed to repair center(it is also a gas station), i was told the the battary was not good and the charging system(i don't know car, so i don't know how to call it) who pass the electricity to battary didn't work for the battary, need to replace both of them, the cost was around $400. Because i don't know about the car, i don't know whether the car repair center ripped me off. this was my first car repair experience. This time my car has problem again, three lights (check, vsc and vsc off)on when i am driving the car. this time i did the search from internet before i went to the car repair center. First i went to the toyota dealer service, i just want to know what's wrong with my car, but i was told the diagnosis will charge me $220, it is too expensive. i went back home then went to another car repair center, they charged me $35 for the trouble code. the trouble code is p0171. The DTC detecting condition said: when air-fuel ratio feedback is stable after engine warming up. fuel trim is considerably in error on rich side. The guy told me: the trouble areas are 1)open or short in A/F sensor(bank1,2 sensor1) circuit 2/A/F sensor(bank1,2 sensor 1). so i need to buy two sensors, the sensor price from toyota dealer is $207 each, he said if i repair the car all from him, the total charge is $405(the parts also from toyota dealer,he said he will give me $187 each). sign, i am really bad luck, the car always give me trouble, like a momey eater. Now my questions are:

1)does three lights on, and trouble code is p0171, show the problem what the guy told me, and i need to replace two sensors? or maybe any other problems? like air indcution system problem, if so ,is it a serious problem? 2)if i don't repair it , will they hurt my car, and lead the big trouble later on? 3)should i go to toyota dealer's service or the place i mentioned above or other shop. i know from dealer the repair cost is more expensive than other personal repair center. i don't have ideal how expensive will be which compare to other shop.but i think the toyota dealer is more trustable, they won't do bad thing on my car?should i have this kind of thoughts, i had bad experience before? Thanks everybody here can help me, i am a female and i don't know about the car,i am the only driver in my family. so i really need your help me to tell me what i should do. thanks again. jennifer
Reply to
jenshi
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The Diagnostic Trouble Code (DTC) P0171 means that the air-fuel ratio is too lean, not too rich. When the air-fuel ratio is too lean, it means that there is not enough fuel in the air-fuel mixture.

I do not think you need to replace 2 sensors. A competent technician should test the sensor before replacing it to prevent unnecessary replacement of parts.

I'm not sure what your guy meant by "A/F" sensor. If he meant air flow sensor, then I do not agree with his diagnosis because an open or a short in the air flow sensor would give a different DTC.

It is possible that the mass air flow sensor is bad, it is also possible that the oxygen sensor is bad. In either case, it is possible to test the sensors instead of blindly replacing them to see if the problem goes away.

Yes. The vehicle will not pass an emissions test, and a lean fuel mixture can damage the engine's valves.

The Toyota dealer may be less expensive in the long run since they are not as likely to blindly replace unneeded parts. If you decide to go to an independent technician, go to a shop with ASE certified technicians or that is AAA approved.

Reply to
Ray O

thanks for reply. i did feel strange that the guy even didn't start the engine, and used the palm analyzer to test it, just 30 seconds, and printed the trouble code from DVD. then told me to change two sensors, he even didn't do any further check up to make sure that it is really the sensors (he said O2 sensors)that go wrong. i just felt something uncomfortable, so i went back home, go to the internet to seek the help.

Ray O wrote:

Reply to
jenshi

The engine does not need to started to scan trouble codes.

then told me to change two sensors,

The trouble codes tell the technician what to check, not to change ;-)

Reply to
Ray O

Reply to
turk

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