Code 171, . A long story. Help


Old 11-05-06, 07:38 PM
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Join Date: Apr 2001
Location: USA
Posts: 18
Code 171, . A long story. Help

The car is a 2000 Chevy Prizm. The engine light is on and I checked the OBD II for the code. It gave me code 171 whitch is lean mixture according to its service manual. Involved is the MAF sensor, O2 sensor, Computer, and other engine parts .The testing and diagnoseses required more test equipment than I have. Knowing how expencieve parts are I thought I better get a good diagnoses.First stop was my favorite auto repair shop . He told me its code 171 and that he had cleared it ,and did not know why it was on. I already knew this . He charged me $15.00 and said go to a dealer. So I took it to the dealer I bought it from . Three days later and a lot of their time spent on it he told me the MAF sensor was not at its correct values but that it tests out OK . So his diagnoses was that it was a exhaust blockage problem and charged me $90.00 . OK I firgured its a pluged Catalitic converter. I bought one and installed it , however the old one realy didn't look bad on the inside. I then cleared the code and drove the car. Guess what ! the code came back. Obviously he was wrong. Now what do I do ? Start throwing parts at it ? The car is actualy a Toyota Corola in Chevy disguise, so should I take it to a Toyota Dealer for diagnoses ? Any help will be greatly appreciated.
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Old 11-06-06, 03:45 PM
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Join Date: Feb 2001
Location: SW Fla USA
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Well, first off, I would avoid the two shops you've already been to in the future. Any decent shop should be able to diagnose and fix problems like yours. A plugged cat would not have been on my short list of possible problems on a 6 year old car. If you don't have a line on a good independent, then a Toyota dealer might be the way to go for you.
Old 11-06-06, 04:37 PM
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Join Date: Apr 2001
Location: USA
Posts: 18
Thanks for your help. I decieded to go with my first inclanation and throw parts at it. First part is the MAF sensor and that will be in tomorow. Next part will be the Pre cat O2 sensor.
Old 11-06-06, 05:16 PM
Join Date: Nov 2006
Posts: 3
sensor check

just had the 172 code on my ford. it was the o2 sensor on bank1(v8) 171 is Bank2 has your gas mileage dropped?
if o2 is bad the computer thinks it is running lean and adds fuel.
Old 11-07-06, 08:19 AM
Join Date: Jun 2006
Location: USA
Posts: 110
Had s similar problem on my 99 Taurus recently. Turned out to be a bad connection on the MAF. MAF itself OK but the bad connection was skewing the signal to the computer, which in turn commanded an incorrect fuel mixture. Fixing it not only cleared the SES dash light, but significantly improved mileage.

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