# cel codes



## vic vickery (Nov 29, 2005)

hello all. I'm a newbie here so bear with me. I have a 97 altima. The check engine light recently came on with codes 171 fuel injection system lean, 325 knock sensor, 420 catalyst efficiency or three way catalyst (not sure). Any thoughts on how to proceed to remedy this. I have crawled under the car to take a look at where the knock sensor is. Looks almost impossible to get to it. have not disconnected and tested resistance yet. could bad knock sensor cause the other codes as knock sensor retards timing. engine seems to run fine with no discernible spark knock or rattle. any thoughts appreciated..vic


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## KA24Tech (Feb 2, 2004)

First try replacing the fuel filter and then the O2 sensor. The knock sensor code is probably from the lean condition.

Troy


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