How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Chris (aka-Moose) Your Own Question
Chris (aka-Moose)
Chris (aka-Moose), Technician
Category: Honda
Satisfied Customers: 43915
Experience:  16 years of experience
Type Your Honda Question Here...
Chris (aka-Moose) is online now
A new question is answered every 9 seconds

Honda 2000 GX with codes P0300,P0301,P0302,P0303,P0304,and

This answer was rated:

Honda 2000 GX with codes P0300,P0301,P0302,P0303,P0304,and stumped on P1399

Hello, I'm Chris. Thanks for visiting Just Answer.


I am sorry you have had to wait so long for the first contact. Sometimes this happens when the question you ask is not detailed enough or its just hard to address online. Many have viewed your post, but have decided to pass.

I will do my best to help you. I have access to many repair sites, so at the least I can provide something to address at least part of your concern if it is not something I can address from memory and experience.

I mainly work in the last half of the day 2pm-midnight cst. , so that is when I do all of my responding.

Once you get an answer, you will be prompted to rate me. You are rating my help, not the website, or answer. If you feel the need to rate negative, please save the rating so I can try again or find someone whom may be able to help better.

Thanks for using our site, we will do all we can to earn your business, again sorry we did not get to you sooner.

X Do you still need help?

X Is there any more information you can add?

X At minimum what do you need to know if I can not address all of your concern?


Customer: replied 3 years ago.

Yes I still need help.


I also changed the Coalescent filter. The car starts and all seems OK then after approx. a mile the intermittent miss starts, and is at times seems to run OK then hesitates and misses.

What is causing the random misfire - and does that require changing all 4 of the injectors @ $160 each?

I recommend you check and verify there is good fuel pressure while this misfire is occurring. Trouble code P1399 is a random misfire code displayed by some Honda vehicles. Some scan tools will display P1399 instead of P1300. Check the fuel trims to see if the MAP sensor has a concern and is adjusting the air fuel ratio incorrect.


Chris (aka-Moose) and 3 other Honda Specialists are ready to help you
Customer: replied 3 years ago.

The 2000 GX has 100,090 miles and was serviced by Honda dealership @ 79,393 mi and replaced 4 injectors ($2,526 parts) and @ 80,461 mi replaced the fuel pressure regulator ($2,099 parts). along with an EGR valve ($294 part).

I used an OBD-II to get the codes for intermittent misfire, and it seems to occur on each cylinder. I have the Honda GX supplement service manual, but unsure of tracking the MAP sensor. Appreciate any assistance with tracing this problem.


Chris (aka-Moose) and 3 other Honda Specialists are ready to help you
Customer: replied 3 years ago.

Thanks Moose,

You've given me info to review and pursue. Sorry about the delay

Glad I could help