The 4th injector is causing a problem for these high mileage 2017+ Duramax 6.6L trucks. On this Diesel Insights, Nick gives you a good tip that costs nothing to alleviate these P0204 P026D and P0300 codes that arise when this pigtail has issues. Have any idea why it's always the 4th injector? Leave a comment, let's hear your theories.
