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Forum > Failed Smog Test > Question

Trouble Code P0325 and P0330 Knock Sensor Fault

My Lexus ES300 failed the smog test because the smog machine could not read Diagnostic Codes (Emission Monitors) because of a recent battery disconnect. The tailpipe emission were well within limits.

After the smog failure the VIR report showed trouble code P0325 and P0330. Apperently something is wrong with my Lexus's knock sensors. These codes DO NOT illuminate the Check Engine Light (CEL) however. Will these DTC codes cause my car to fail the next smog test, even though I pass the measured emissions and the CEL light is off? Thank you for your time.

Answer:

Although the knock sensor trouble codes have not trigged the check engine light on (yet) they will cause a smog check failure if the codes exist within the ECU during the smog inspection. Knock sensor trouble codes P0325 and P0330 are usually 2 trip codes. Before they trigger the check engine light on they must be verified at least twice. In this specific case it appears there is either an engine problem causing these fault codes to trigger or possibly something wrong with the knock sensor(s) themselves. posted by SmogTips Support

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