Code 647 is a fuel trim problem. Before checking both codes need to verify ECU connector and harness are good. Make sure there are no breaks or damage.
Verify fuel quality. Inspect gasoline for contaminants or verify LP is certified HD-5 or HD-10 and there are no
known fuel issues.
Is fuel contaminated?
YES: Replace with correct / certified LP. Drain gasoline, flush system, and use new fuel source.
NO: Proceed to Step 2.
2. Inspect fuel delivery system for leaks or damage. Inspect storage tank, delivery lines, rails, and other fuel
components.
Is fuel system damage evident?
YES: Repair fuel system / component, clear DTC and retest system.
Inspect exhaust system components for damage. Ensure no restrictions or leaks are present.
Is an exhaust fault present?
YES: Repair or replace exhaust system, clear DTC and retest system.
Inspect air filter and air induction system. Ensure no damage or restrictions are present.
Is an air restriction present?
YES: Repair or replace faulty air induction component.
If no faults are evident and fault code remains, replace faulty mixer or fuel regulator.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.