A.O. Smith 110-310-510 – ERROR CODE 101[510 (T-D2)], FIVE FLASHES/10 [110 (T-KJR2), 310 (T-K4)] ABNORMAL COMBUSTION

1) Blockage in the airway. Check the following areas:
a. Venting length obstruction (Birds’ nests, trash, etc.)
b. Backflow preventer installed backwards
c. Heat exchanger
d. Fan
2) Check the manifold pressure (p. 22). Adjust the manifold pressure to the correct values if necessary.
3) If intake air is contaminated with dust, lint (laundry machine nearby), grease (kitchens), or other contaminants, clean the burner. See p. 26 on procedures for cleaning the burner & rod assembly.
4) Weather related issues: high winds, frozen vent termination flap, etc.
5) Installations at altitudes around or over 3000 feet: Change dipswitches on the computer board for FM+ modes. See dipswitch explanations on page 19.
6) Make sure all dipswitches are set properly for the type of installation.
7) If the cause of the 101 error code has been determined and solved, reset the computer board to clear the error code (p. 23).