Check engine light flashing with codes P0301, P0303, P0300 and P1399

1998 HONDA ACCORD

256,000 MILES • 2.3L • 4 CYL • 2WD • AUTOMATIC

GORDON2

MEMBER
76 POSTS

My car has been running rough recently and I thought it was having trouble shifting. It has been inconsistent. Today the check engine light started flashing. I have 3 confirmed codes and 1 pending code. The confirmed codes are P0301 [Cylinder 1 Misfire Detected], P0303 [Cylinder 3 Misfire Detected], P0300 [Random/Multiple Cylinder Misfire Detected]. I have a Pending P1399 [Manufacturer Defined] code. Where do I start?

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May 13, 2021 at 10:40 AM

ASEMASTER6371

✓Experienced Mechanic
52,796 POSTS

Good evening,

I would start with the basics. Replace the plugs and I would also check the compression to be sure the timing is correct. You should have 140-160 pounds.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/how-to-test-engine-compression

I would also check the fuel pressure low pressure from a bad fuel pump will cause these misfire codes.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Roy

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May 13, 2021 at 12:04 PM

JIS001

✓Experienced Mechanic
3,412 POSTS

With the mileage on your vehicle I would strongly recommend a valve lash adjustment. Normally the exhaust valves get too tight and hold the valve open too long where you will get the random misfire. You will also see it in the fuel trims being in the negative number indicating too rich.

The valve adjustment needs to be done when the engine is at room temperature. If you need instructions let us know and one of our colleagues will post it up.

May 13, 2021 at 4:15 PM