2009 Patriot P0300 - JeepForum.com
LinkBack Thread Tools
post #1 of 3 Old 09-11-2021, 12:40 PM Thread Starter
Registered User
Join Date: Sep 2021
Posts: 2
2009 Patriot P0300

Looking for some thoughts here.. I have an 09 Patriot that throws a P0300 (only code thrown) when rpms rise above 2k or so... If I clear the code it seems fine for a few min OR rises above 2k rpms.... At that point the ECU seems to shut off the injector pulse... to at LEAST cylinder 1 (my crappy Autel scan tool for some reason ONLY shows cylinder 1 pulses) Before I dig in has anyone had this same problem? I know coils, plugs first then compression test.. no smoke out back, oil is fine... Thoughts>?

Thanks in advance!

Tesadorn is offline  
Sponsored Links
post #2 of 3 Old 09-11-2021, 01:26 PM
Registered User
jtec's Avatar
2014 JK Wrangler 
Join Date: Oct 2017
Posts: 10,442
I am not familiar with that scanner.
P0300 often has accompanying codes, If you can look and see if there is any helpful info in 'freeze frame'
YES simply put The system will disable the offending cylinder. WHY a multi cyl code and affecting only #1 IDK, my guess scanner ability.

Maybe a second opinion so to speak - with CEL on take advantage of FREE scans at most auto part stores. Did I mention FREE

P0300 - any recent work? If you scanner does not have live data - checking fuel pressure and plug condition.
Looking at data - ECT, MAP, fuel trims long and short, and pre cat o2 sensors.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #3 of 3 Old 09-12-2021, 09:44 PM Thread Starter
Registered User
Join Date: Sep 2021
Posts: 2
Looks like it was the relay marked "main"..swapped it cleared codes and drove for 30 min...time will tell...
Tesadorn is offline  

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome