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How to fix the Navien error code 003?

Alton Alexander
By Alton AlexanderUpdated on June 4th, 2022

Navien error code 003 is a common error code that can occur for a variety of reasons. Some of the most common reasons include a clogged venturi, a dirty or damaged heat exchanger, or a faulty pressure switch. This error code can also be caused by a variety of other factors, so it is important to troubleshoot the problem before attempting to fix it.

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1. Check the water pressure

  1. Open the water valve by turning it counterclockwise.
  2. Look at the water pressure gauge to see if it reads high or low. If the pressure is high, turn the water valve counterclockwise until it reads low. If the pressure is low, turn the water valve clockwise until it reads high.
  3. If the water pressure still does not read correctly, turn the water valve all the way off and then back on. If the water pressure still does not read correctly, call a professional.

2. Clean the inlet filter

  1. Open the navien machine and locate the inlet filter.
  2. Remove the old inlet filter.
  3. Clean the filter with a clean cloth.
  4. Replace the inlet filter.

3. Check the gas pressure

  1. Check the fuel level in the tank. If there is not enough fuel, the engine may not be getting the fuel it needs to run properly and may give the navien error code 003.
  2. Check the gas pressure. If the gas pressure is low, the engine may not be getting the fuel it needs to run properly and may give the navien error code 003.
  3. Check the air filter. If the air filter is dirty, the engine may not be getting the air it needs to run properly and may give the navien error code 003.
  4. Check the fuel filter. If the fuel filter is dirty, the engine may not be getting the fuel it needs to run properly and may give the navien error code 003.
  5. Check the spark plugs. If the spark plugs are not firing properly, the engine may not be getting the spark it needs to run properly and may give the navien error code 003.

4. Clean the combustion chamber

  1. Remove the spark plugs and the air filter.
  2. Clean the entire combustion chamber with a degreaser and a brush.
  3. Wipe the chamber clean with a dry cloth.
  4. Reinstall the spark plugs and the air filter.
  5. Start the engine and check the navien error code 003.

Still not working? maybe try:

  1. Replace the gas valve.
  2. Replace the pressure relief valve.
  3. Replace the control board.