1997 Nissan 200SX P0325 and P1400 Fault Diagnosis: Knock Sensor & Circuit Issues
I own a 1997 Nissan 200SX (Series 2.0L). After retrieving fault codes P0325 and P1400, I replaced the knock sensor solenoid and the three associated hoses—particularly the bottom hose, which was found clogged. After clearing the codes, both faults returned within just 10 miles of driving. I then had a friend attempt to remove the original knock sensor, which engineers noted was installed in an extremely hard-to-access location. Due to the difficulty, I instead used the existing sensor plug and installed a new knock sensor near the throttle body. Despite this modification, the check engine light remains on with the same codes. I'm seeking advice on how to properly diagnose and resolve these persistent issues.
A fault code does not automatically mean a part needs replacement. For P1400, begin by checking the electrical circuit—verify the fuse, wiring, and electrical connectors. For P0325 (knock sensor), first review the freeze frame data, then inspect the sensor harness and all connections. The knock sensor should read approximately 500–620 kΩ at 77°F. Confirm there are no exhaust leaks, engine noise such as tapping or ticking, or signs of spark knock.