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Error code reference

Electrolux Range Error Code 21

LIN (Local Interconnect Network) error, no communications or shorted bus on ESEC cooktop.

Electrolux codesElectrolux range codes

LIN (Local Interconnect Network) error, no communications or shorted bus on ESEC cooktop.

First step from the service manual

Verify the LIN Bus communication harness at ESEC-UIB P8 connector is well connected and not damaged. Replace ESEC-UIB. Replace Filter Circuit Board.

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

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What 21 means on a Electrolux range

Error code 21 on an Electrolux range indicates a LIN (Local Interconnect Network) communication failure on the ESEC (Electrolux Smooth Electric Cooktop) system. The LIN bus is a low-speed serial communication network that allows the User Interface Board (UIB) to exchange data with other cooktop control components. When the range detects no communication on this bus, or detects a shorted bus condition, it triggers error code 21 and typically disables cooktop operation to prevent unsafe conditions.

The ESEC-UIB P8 connector is the primary junction point for the LIN bus harness. A loose, corroded, or damaged connector at this point is the most common cause of this fault. A shorted bus condition can result from pinched or damaged wiring within the LIN harness, which can pull the bus voltage to an abnormal level and prevent any communication from passing between components. Physical damage to the wiring from heat exposure near cooktop elements is a realistic failure scenario.

If inspecting and reseating the harness at the P8 connector does not resolve the fault, the ESEC-UIB itself may have an internal failure that prevents it from communicating correctly on the LIN network. The Filter Circuit Board is also implicated in this error, as it conditions power and signals for the cooktop control system, and a failure there can disrupt communication entirely. Diagnosis should proceed from the harness connection first, then component replacement in the order specified.

Source: manufacturer service documentation.

Common causes of 21

  1. 01

    Loose or disconnected LIN bus harness at P8 connector

    Wiring / connection

    The LIN bus harness connection at the ESEC-UIB P8 connector may have loosened over time due to vibration or installation handling. Reseating the connector firmly is the first and most likely fix for this error.

  2. 02

    Damaged or shorted LIN bus wiring

    Part replacement

    The wiring within the LIN harness may be pinched, burned, or chafed, causing a short that pulls the bus voltage to an abnormal level and halts all communication. Inspect the harness routing near heat sources and sharp edges for visible damage.

  3. 03

    Failed ESEC-UIB (User Interface Board)

    Part replacement

    An internal failure in the ESEC-UIB can prevent it from transmitting or receiving LIN bus signals even when the wiring is intact. If the harness checks out, the UIB is the next component to replace.

  4. 04

    Failed Filter Circuit Board

    Part replacement

    The Filter Circuit Board conditions power and signals for the cooktop control system. A failure here can disrupt LIN bus communication and produce error code 21 even if the harness and UIB appear functional.

See the test procedure for each cause

Frequently asked questions about 21

What does 21 mean on a Electrolux range?
Error code 21 on an Electrolux range signals a LIN (Local Interconnect Network) communication failure on the ESEC cooktop system. This means the cooktop's User Interface Board either cannot communicate with other control components or has detected a shorted condition on the communication bus. The cooktop may be disabled until the fault is resolved. The most common starting point is inspecting the LIN bus harness at the ESEC-UIB P8 connector.
Can I fix error code 21 on my Electrolux range myself?
A knowledgeable DIYer can attempt the first diagnostic step, which involves checking that the LIN bus harness at the ESEC-UIB P8 connector is securely connected and undamaged. If the connector is seated correctly and the wiring appears intact, resolving the fault will likely require replacing the ESEC-UIB or the Filter Circuit Board, which involves working with internal range electronics. If you are not comfortable working with appliance wiring and control boards, a qualified technician is recommended.
Is it safe to use my Electrolux range while error code 21 is displayed?
Error code 21 typically disables the ESEC cooktop to prevent unsafe operation during a communication failure. The oven section may or may not be affected depending on your model. It is best to avoid using the cooktop until the fault is diagnosed and repaired, as operating with a compromised control communication network can be unpredictable.
Will resetting my Electrolux range clear error code 21?
Resetting the range by cutting power at the breaker for a few minutes may temporarily clear error code 21, but it will return if the underlying cause is not addressed. A loose connector that reseats itself during a power cycle might stay clear longer, but a shorted harness or failed board will cause the fault to reappear quickly. A reset is useful for confirming the error is persistent, but it is not a repair.
How much does it cost to repair error code 21 on an Electrolux range?
If the fix is simply reseating the LIN bus harness connector, the repair may cost nothing beyond a service call fee, which typically ranges from $75 to $150. If the ESEC-UIB or Filter Circuit Board needs replacement, parts costs generally range from $100 to $300 or more depending on the specific board and model, plus labor. Getting a diagnostic visit from a technician before ordering parts is advisable to confirm which component has failed.

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