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Error code reference

Thermador Range Error Code Er:20

WFR 2460 washer

Thermador codesThermador range codes

WFR 2460 washer: Turbidity sensor fault (via analogue sensor, calibration not possible).

First step from the service manual

Start T/P 10 sensor test programme.

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

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What Er:20 means on a Thermador range

Er:20 on a Thermador range equipped with the WFR 2460 washer module indicates a turbidity sensor fault detected through the analogue sensor circuit. The turbidity sensor monitors the clarity of water used during wash cycles by measuring light transmission or resistance changes through the water column. When the control module cannot obtain a valid analogue signal from this sensor, it flags Er:20 and halts normal operation. Critically, the fault is classified as one where calibration cannot be performed, meaning the system is receiving a signal that is either absent, out of acceptable range, or corrupted beyond the point where software correction can compensate.

The turbidity sensor itself is an analogue device, so the fault pathway includes the sensor element, the wiring harness connecting it to the control board, and the input circuit on the control board that interprets the analogue voltage or resistance reading. A failed sensor will typically produce no signal or a signal that is fixed at one extreme. A wiring issue such as a broken wire, corroded connector pin, or short to ground will similarly produce an invalid reading. Because the system explicitly notes that calibration is not possible, the root cause is almost certainly a hard electrical fault rather than simple sensor drift.

The recommended first diagnostic step is to run the T/P 10 sensor test programme, which exercises the sensor circuit under controlled conditions and allows the technician to observe live analogue output values. This test helps isolate whether the fault is in the sensor itself, the harness, or the control board input stage. Resistance checks across the sensor terminals and continuity checks along the harness should follow if the test programme confirms an abnormal reading.

Source: manufacturer service documentation.

Common causes of Er:20

  1. 01

    Failed turbidity sensor

    Part replacement

    The analogue sensor element itself has failed, producing no output or a fixed out-of-range signal. This is the most common cause when wiring checks out normal and the T/P 10 test programme shows an absent or pegged reading.

  2. 02

    Corroded or damaged connector at the sensor

    Wiring / connection

    Moisture exposure in the wash module environment can corrode the sensor connector pins, creating high resistance or an open circuit. Inspect the connector for discoloration, pin retraction, or oxidation.

  3. 03

    Broken or shorted wiring harness

    Part replacement

    A wire in the harness between the turbidity sensor and the control board may be broken or shorting to ground, causing the analogue input to read incorrectly. A continuity and isolation test along the full harness length will identify this.

  4. 04

    Contaminated sensor lens or sensing element

    Wiring / connection

    Heavy scale buildup or debris coating the sensor's optical or resistive element can block accurate readings. Inspect the sensor face for deposits and clean carefully before condemning the sensor.

  5. 05

    Control board analogue input circuit fault

    Part replacement

    If the sensor and harness both test within spec during T/P 10 diagnostics, the analogue input stage on the control board may be damaged. This is the least common cause but should be considered after all other components are ruled out.

See the test procedure for each cause

Frequently asked questions about Er:20

What does Er:20 mean on a Thermador range?
Er:20 indicates a turbidity sensor fault in the WFR 2460 washer module. The analogue sensor that monitors water clarity is either not producing a readable signal or producing one that falls outside acceptable limits. The control system also determines that calibration cannot correct the fault, pointing to a hard electrical or component failure rather than simple drift.
Can I fix Er:20 myself, or do I need a technician?
A knowledgeable DIYer can start by inspecting the sensor connector for corrosion and cleaning the sensor element for scale buildup, as these steps require no special tools. However, running the T/P 10 sensor test programme requires access to the service diagnostic mode, and interpreting the analogue output values requires some technical familiarity. If the sensor or wiring needs replacement, a technician is recommended to ensure correct component handling and reassembly.
Will resetting the appliance clear the Er:20 fault?
A power reset may temporarily clear the error code from the display, but if the underlying sensor or wiring fault is still present, Er:20 will return once the wash cycle attempts to read the turbidity sensor again. The fault must be diagnosed and repaired at the hardware level to permanently resolve it.
Is it safe to use the appliance while Er:20 is active?
Running the wash cycle with an active turbidity sensor fault means the system cannot monitor water clarity, which can result in poor wash performance or improper cycle termination. It is best to avoid running wash cycles until the fault is resolved to prevent further issues or potential damage to the wash system components.
How much does it cost to repair an Er:20 fault on a Thermador range?
Repair costs vary depending on the root cause. Cleaning a contaminated sensor or repairing a connector costs very little beyond labor, typically in the range of $50 to $150 for a service call. Replacing the turbidity sensor itself generally runs $100 to $300 including parts and labor. If the control board analogue input circuit is the cause, board replacement can push total costs into the $300 to $600 range or higher depending on part availability.

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