Posts

All the articles I've posted.

• A.O. Smith Tankless E04 Error - Causes & Fix

  31 May, 2026

  E04 on an A.O. Smith electric tankless water heater means moisture or a leak is detected inside. Turn off power and water, then call support.

• A.O. Smith Tankless E02 Error - Causes & Fix

  31 May, 2026

  E02 means over-temperature: heated water exceeded the limit. Most often caused by low flow or a failing thermistor. Here's how to fix it.

• Rinnai LC Error Code - Causes & Fix

  31 May, 2026

  LC code means scale buildup in the heat exchanger. Flush the unit with descaling solution to clear the code and restore full operation.

• Navien E782 Error Code - Causes & Fix

  31 May, 2026

  E782 means abnormal main panel communication. Usually caused by a failed PCB or loose connector. Check wiring first, replace board if needed.

• Navien E777 Error Code - Causes & Fix

  31 May, 2026

  E777 means abnormal LWCO operation on Navien combi units. Most often it's a loose LWCO wire or low water level on the heating side.

• Navien E740 Error Code - Causes & Fix

  31 May, 2026

  E740 means outdoor temperature sensor failure. Check sensor wiring and outdoor reset configuration, or replace the sensor if damaged.

• Navien E615 Error Code - Causes & Fix

  31 May, 2026

  E615 signals an abnormal control-board or input/memory fault. Most likely fix is to power-cycle the unit and replace the PCB if it returns.

• Navien E594 Error Code - Causes & Fix

  31 May, 2026

  E594 means abnormal EEPROM operation on your Navien tankless heater. The main control board has failed or corrupted memory. Replace the PCB.

• Navien E030 Error Code - Causes & Fix

  31 May, 2026

  E030 means exhaust overheat on your Navien tankless water heater. Most often caused by blocked venting or a clogged inlet filter.

• Siemens G120 F01662 - Causes & Fix

  31 May, 2026

  F01662 means internal communication error inside the drive. Most often fixed by power cycling or replacing the control unit.

• Siemens G120 F01659 - Causes & Fix

  31 May, 2026

  F01659 means the drive rejected a safety parameter write. Most likely fix: enter the correct Safety Integrated password or reset the safety state.

• Siemens G120 F01650 - Causes & Fix

  31 May, 2026

  F01650 means a safety parameter fault. Most often the Safety Integrated acceptance test is incomplete or safety wiring has a problem.

• Siemens G120 F01625 - Causes & Fix

  31 May, 2026

  F01625 means a sign-of-life error in safety data on your G120 drive. Most often caused by EMC interference or wiring issues.

• Siemens G120 F01600 - Causes & Fix

  31 May, 2026

  F01600 means Safety Integrated STOP A initiated on your Siemens G120 VFD. Check STO inputs, read fault value r0949, then cycle power.

• Siemens G120 A01590 Alarm - Causes & Fix

  31 May, 2026

  A01590 means your motor maintenance interval has expired on the G120 VFD. Reset parameter p0651 after performing scheduled motor service.

• Siemens G120 F01250 Fault - Causes & Fix

  31 May, 2026

  F01250 is not a verified Siemens G120 fault code. Confirm the exact code on your drive display, then consult the fault list or call support.

• Siemens G120 F01205 - Causes & Fix

  31 May, 2026

  F01205 means the control unit's CPU ran out of processing time. Power-cycle the drive. If it returns, replace the control unit.

• Siemens G120 F01122 - Causes & Fix

  31 May, 2026

  F01122 (A01122) means frequency at the measuring probe input is too high. Check probe wiring, scaling, and parameters before replacing anything.

• Siemens G120 F01105 - Causes & Fix

  31 May, 2026

  F01105 means the Control Unit has insufficient memory. Most often fixed by reloading parameters or replacing the CU if hardware fails.

• Siemens G120 F01044 - Causes & Fix

  31 May, 2026

  F01044 means the Control Unit cannot load descriptive data from memory. Most common fix: power cycle, reseat memory card, or replace CU.

• Siemens G120 VFD F01040 - Causes & Fix

  31 May, 2026

  F01040 means the G120 drive changed a parameter and needs you to save settings (p0971) then power-cycle the Control Unit to clear.

• Siemens G120 F01034 - Causes & Fix

  31 May, 2026

  F01034 means parameter recalculation failed after a reference value change. Most likely fix: correct incompatible parameters or clear buffer memory.

• Siemens G120 F01033 - Causes & Fix

  31 May, 2026

  F01033 means a reference parameter for unit conversion is invalid (often 0.0). Fix by correcting the scaling parameter in your drive setup.

• Siemens G120 A01028 Fault - Causes & Fix

  31 May, 2026

  A01028 means the drive's saved configuration was made for a different module type. Save parameters with p0971=1 or reload the correct project.