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Error code reference

GE Range Error Code F621

LIN communication error to/from RPSM Aux Board (when equipped).

GE codesGE range codes

LIN communication error to/from RPSM Aux Board (when equipped).

First step from the service manual

Replace Aux board, especially if Main Board relays still function.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What F621 means on a GE range

The F621 error code on a GE range indicates a LIN (Local Interconnect Network) communication failure between the Main Control Board and the RPSM (Remote Power Supply Module) Auxiliary Board. LIN is a serial communication protocol used to coordinate data between control modules within the appliance. When the Main Board cannot establish or maintain a valid communication signal with the Aux Board, it logs this fault and may disable certain functions to protect the system. This code only applies to ranges equipped with the RPSM Aux Board configuration.

The most common cause of F621 is a failed Aux Board itself. Because the first diagnostic step specifically notes that Main Board relays still functioning is a key indicator, technicians should verify relay operation before replacing the Main Board. If the burners and oven respond normally to inputs but the F621 code persists, the Aux Board is the primary suspect. A failed Aux Board will be unable to respond to LIN polling from the Main Board, triggering the communication fault.

Secondary causes include wiring harness faults between the two boards, such as damaged connectors, broken wires, or loose pins in the LIN communication circuit. Corrosion or moisture intrusion at connector terminals can also interrupt the signal. In rare cases, the Main Board itself may be unable to initiate proper LIN communication, though this is less likely when its relay functions remain intact.

Source: manufacturer service documentation.

Common causes of F621

  1. 01

    Failed RPSM Aux Board

    Part replacement

    The Aux Board is the most likely cause when the Main Board relays still function normally. A failed Aux Board cannot respond to LIN communication signals, causing the F621 fault to trigger.

  2. 02

    Damaged or Loose Wiring Harness

    Wiring / connection

    A broken wire, loose connector pin, or damaged harness between the Main Board and Aux Board can interrupt the LIN communication signal. Inspect all connectors for secure seating and visible damage.

  3. 03

    Corroded Connector Terminals

    Wiring / connection

    Moisture or grease contamination on the LIN circuit connector terminals can cause high resistance or open circuits. Clean or replace affected connectors if corrosion is visible.

  4. 04

    Failed Main Control Board

    Part replacement

    In less common cases, the Main Board may lose the ability to initiate LIN communication even while its relay outputs remain operational. This is considered after the Aux Board and wiring have been ruled out.

See the test procedure for each cause

Frequently asked questions about F621

What does F621 mean on a GE range?
F621 indicates a LIN communication error between the Main Control Board and the RPSM Auxiliary Board. LIN is a serial data protocol the boards use to coordinate operation. This code only appears on GE ranges equipped with the RPSM Aux Board. The fault typically points to a failed Aux Board or a wiring issue between the two boards.
Can I fix F621 on my GE range myself?
If you are comfortable working with appliance electronics, you can inspect the wiring harness and connectors between the Main Board and Aux Board for loose or damaged connections. However, if the wiring appears intact, the Aux Board will likely need to be replaced, which requires identifying the correct part and safely accessing the range's control area. Many homeowners prefer to have a qualified technician handle board-level repairs.
Is it safe to use my GE range when F621 is displayed?
The F621 code is a communication fault rather than an immediate fire or safety hazard. However, the Aux Board failure may affect certain range functions or cause unpredictable operation. It is best to limit use of the appliance until the fault is diagnosed and repaired to avoid potential secondary issues.
Will resetting my GE range clear the F621 error?
Resetting the range by disconnecting power for a few minutes may temporarily clear the F621 code, but it will return if the underlying communication fault is not resolved. The Aux Board or wiring issue causing the fault must be addressed for the code to stay cleared.
How much does it cost to repair a GE range F621 error?
Repair costs depend on whether the fix is a wiring correction or a board replacement. If only connector cleaning or harness repair is needed, costs may be relatively low, primarily covering labor. If the Aux Board requires replacement, parts plus labor can range from around $150 to $400 or more depending on the specific model and service rates in your area.

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