1996 Cadillac DeVille P0171 and P0174

1996 Cadillac DeVille

Cadillac DeVille On the 1996 Cadillac DeVille, when P0171 and P0174 are set with oxygen sensor codes, more times than not, this is not an oxygen sensor problem. This means the air-fuel mixture is running “lean” and this is what sets the oxygen sensor code. It’s not very common for both upstream oxygen sensors to fail at the same time. So, before condemning the oxygen sensors – First- check the Fuel Filter. Remove the filter and try to blow through it. Any resistance and the Fuel Filter will need to…

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