Fixing Navien Error Code 515-09: Abnormal PCB

Navien tankless water heaters are known for their efficiency and reliability, but occasionally, they may display error codes that indicate an issue with the system. One such error is code 515-09, which suggests an abnormality with the PCB (Printed Circuit Board). In this article, we will explore the causes of Navien error code 515-09 and provide solutions for fixing this issue.

Understanding Navien Error Code 515-09

Error code 515-09 appears when there’s a problem with the PCB, responsible for controlling and monitoring the various functions of your Navien tankless water heater. The PCB serves as the central hub of the unit, and any issues with it can lead to malfunctions and reduced performance.

Causes of Navien Error Code 515-09

Several reasons can cause error code 515-09 to appear on your Navien tankless water heater:

  1. Faulty or damaged PCB: A damaged or malfunctioning PCB can cause the error code 515-09 to appear. This might be due to a manufacturing defect, power surge, or exposure to moisture.

  2. Improper wiring connections: Loose or incorrect wiring connections can result in abnormal PCB behavior and trigger the error code.

  3. Electrical interference: External electrical interference from nearby devices or appliances can cause issues with the PCB, leading to error code 515-09.

Fixing Navien Error Code 515-09: Abnormal PCB

Step-by-Step Guide to Fixing Navien Error Code 515-09

Follow these steps to troubleshoot and fix error code 515-09 on your Navien tankless water heater:

step 1: Reset the system

Reset the system by turning off the power to the unit, waiting for a few minutes, and then turning it back on. This simple reset can sometimes clear the error code and restore normal operation.

Step 2: Check wiring connections

To start dissecting this enigma, turn your attention to the Printed Circuit Board (PCB). Following the removal of the unit’s front guard, the PCB’s location will be apparent. Each wiring connection should be inspected meticulously for signs of instability or disconnection. Discovering any such irregularities, apply the appropriate corrective measures with a screwdriver.

Step 3: Purify the Aqua Filter

Should the connections be found robust and the mystery remains, your investigative path leads next to the water filter. Having ensured that the unit’s water supply and power are both disengaged, proceed to the filter’s extraction. Its purification should be undertaken gently yet thoroughly, using a soft bristle brush or cloth before reinstallation.

Step 4: Examine the Propeller Engine

Persisting difficulties necessitate the examination of the fan motor, conveniently located adjacent to the PCB. This essential component warrants inspection for its operational fluidity and absence of abnormal auditory indications. An uncooperative motor is an unfortunate finding, often indicative of the need for substitution.

Step 5: Substitute the Printed Circuit Board

Persistent trouble despite the prior interventions necessitates the contemplation of our final solution: PCB replacement. This endeavor is substantially more intricate and is best managed with expert assistance. Reach out to a certified technician or the Navien customer support to guide you through this labyrinth.

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Preventing Future Issues with MorePCB’s Expert Tips

Take the following precautions to prevent future occurrences of error code 515-09:

  1. Install a surge protector: A surge protector can protect your Navien tankless water heater from power surges, which can damage the PCB and cause error codes.

  2. Regular maintenance: Regular maintenance, such as cleaning and inspecting the unit and its components, can help identify potential issues before they become severe problems.

  3. Keep the unit dry: Ensure your Navien tankless water heater is installed in a dry and well-ventilated area to prevent moisture damage to the PCB.

  4. Choose high-quality PCBs: Opt for high-quality PCBs from trusted manufacturers like MorePCB to ensure the best performance and durability for your water heater system.


Error code 515-09 on your Navien tankless water heater indicates an abnormality with the PCB. By following the troubleshooting steps outlined above and utilizing MorePCB’s expertise, you can effectively diagnose and fix this issue. If you’re unable to resolve the problem, consult a professional technician or reach out to MorePCB for assistance. By choosing high-quality PCBs and following preventive measures, you can ensure the optimal performance and longevity of your Navien tankless water heater system.

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