Make: Honda

Model: Accord

Engine: 3.0L

Year: 2000

Error codes: P0301,P0302,P0303,P0304,P0306,P1399

Knowledge level: I know little about cars

Help needed: Please help me find out what is going on and how to fix it.

  • 1
    These codes simply indicate misfiring cylinders. Could be many things - spark plugs, coils, high tension leads, vacuum leaks, fuel delivery issues, etc. The question is impossible to answer as it stands, you need to be much more detailed or simply seek professional diagnosis. Jun 3, 2016 at 14:19
  • when's the past time a tune up was done. also how many miles? you may be overdue for a valve adjustment.
    – Ben
    Jun 3, 2016 at 16:11
  • I would start by changing the plugs and wires. Jun 10, 2016 at 4:31

1 Answer 1


P1399 HONDA - Random Cylinder Misfire Detected

Source of Information: http://www.autocodes.com/p1399_honda.html

Possible causes - Valve clearance out of range - Blocked EGR (exhaust gas recirculation) Passages

Tech notes: Adjusting the valves will usually fix this

When is the code detected? The control module monitors the crankshaft speed and has detected a misfire condition

Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light) - Lack/loss of power - Hard start - Engine hesitation

P1399 Honda Description When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring. - Valve clearance out of range

The other codes are secondary codes indicating the cylinder that is misfiring. P0306 for example indicates cylinder #6.

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