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Error code reference

Bosch Washer Error Code Er:08

Heater doesn't shut off

Bosch codesBosch washer codes

Heater doesn't shut off — faulty heater or stuck heater relay.

First step from the service manual

Run test P16; check heater and heater relay.

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
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What Er:08 means on a Bosch washer

Er:08 on a Bosch washer indicates that the heating element is failing to shut off when it should. Normally, the control board signals the heater relay to open the circuit and cut power to the heating element once the target water temperature is reached. When Er:08 triggers, the board has detected that the heater is continuing to receive power beyond this point, which points to either a heater that is drawing current abnormally or a relay that has welded its contacts in the closed position and can no longer interrupt the circuit.

The heater relay is the most common root cause. Relays can fail mechanically when their internal contacts fuse together due to repeated high-current switching, leaving the circuit permanently closed and the heater continuously energized. A faulty heating element can also contribute if an internal short is causing unexpected current draw that confuses the control system. Both faults are distinguishable through diagnostic testing.

The first step when this code appears is to run test P16, which is the dedicated heater circuit diagnostic in the Bosch service test program. This test allows a technician to observe heater operation under controlled conditions and isolate whether the fault lies in the heater element itself or in the relay that controls it. Resistance checks on the heating element and inspection of the relay for continuity in the open-commanded state will confirm which component has failed.

Source: manufacturer service documentation.

Common causes of Er:08

  1. 01

    Stuck heater relay

    Part replacement

    The relay that switches power to the heating element can have its internal contacts weld together from repeated high-current switching, leaving the heater permanently energized. Testing the relay for continuity while it is in the open state will confirm this fault.

  2. 02

    Faulty heating element

    Part replacement

    A heating element with an internal short or abnormal resistance can cause the control system to detect unintended current flow in the heater circuit. Resistance testing of the element will reveal whether it is within specification.

  3. 03

    Control board fault

    Part replacement

    If the relay and heater both test within normal parameters, the control board itself may be sending a continuous power signal to the heater circuit or misreading the relay state. This is less common but possible after a power surge or component aging.

  4. 04

    Wiring or connector issue

    Wiring / connection

    Damaged wiring or a loose connector between the control board and the heater relay can create a signal fault that mimics a stuck relay condition. Inspecting the harness for burns, corrosion, or pin backouts is part of a thorough diagnosis.

See the test procedure for each cause

Frequently asked questions about Er:08

What does Er:08 mean on a Bosch washer?
Er:08 means the washer has detected that its heating element is not shutting off as commanded. The fault points to either a stuck heater relay or a faulty heating element in the wash circuit. The control board triggers this code when it determines the heater is staying energized beyond the expected cutoff point. Diagnostic test P16 is used to isolate the exact component responsible.
Can I fix Er:08 on my Bosch washer myself?
Diagnosing this code requires running service test P16 and performing resistance and continuity checks on the heater and relay, which is within reach for experienced DIYers with a multimeter. However, replacing the heater element or a relay mounted on the control board involves working with high-voltage components, so it carries real safety risk if proper precautions are not taken. Many homeowners prefer to have a qualified technician handle this repair.
Is it safe to use my Bosch washer when Er:08 is displayed?
It is not recommended to continue running the washer with Er:08 active. A heater that cannot shut off can overheat the water, potentially damaging laundry, internal components, or in a worst case creating a hazard. Stop using the machine and have the fault diagnosed before running additional cycles.
How much does it cost to repair Er:08 on a Bosch washer?
Repair costs vary depending on which component has failed. A replacement heating element typically runs in the range of $30 to $80 for the part, while a control board replacement can range from $150 to $350 or more for the part alone. Adding labor, a full repair with a technician generally falls between $100 and $450 depending on the faulty component and local rates.
Will resetting my Bosch washer clear the Er:08 code?
A power reset may temporarily clear the code from the display, but it will not fix the underlying hardware fault. If the heater relay is stuck or the heating element is defective, the error will return as soon as the heater circuit is activated again. A proper repair requires diagnosing and replacing the failed component through service test P16.

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