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2000 Honda Civic LX Repeated P1399 and P0304 Codes - Diagnosis and Solutions

Model: 2000 Honda Civic Fault Code: P0304 Posted: 2015-02-02 09:24

I own a 2000 Honda Civic LX and am experiencing recurring fault codes P1399 and P0304. I've already replaced the spark plugs, ignition coil, rotor, cap, wires, and performed valve adjustments. I also swapped the #4 plug and injector to position #1, but the code P0304 did not disappear. The P1399 code continues to appear intermittently. I'm seeking advice on how to properly diagnose this issue. Any insights into potential causes or next steps would be greatly appreciated.

Related fault codes
P0304P1399
Comments (1)
Anonymous 2015-02-02 10:16

Check the injector wiring at cylinder #4—there may be a loose connector. Also, inspect the #4 spark plug: is it wet, dry, black, or tan? Ensure you're using the correct type of spark plugs for your 2000 Honda Civic LX. Using an OBD2 scanner to review live data such as ECT (Engine Coolant Temperature), fuel trims, and MAP (Manifold Absolute Pressure) readings can provide valuable insights. A fuel pressure test may also help identify any leaks or abnormal pressure issues.