What Does Error Code E42 Mean on a Bosch Washing Machine?
Perform a power reset by switching the machine off at the wall, waiting 5 minutes, then switching it back on — this clears temporary control board glitches and allows the door lock solenoid to reset, often releasing the door immediately (takes about 5 minutes).
Fault description
Error code E42 signals that your Bosch washing machine has encountered a problem releasing the door lock. The door interlock is a safety component that keeps the door sealed during a wash cycle; when the machine finishes and attempts to disengage the lock, it expects confirmation that the mechanism has moved to the open position. If that confirmation never arrives, E42 is displayed.
When this error occurs, the machine will typically stop responding to further commands, the door will remain physically locked, and the cycle will not progress. In some cases the drum may still contain water, which can prevent the lock from releasing as a deliberate safety measure. Understanding which of these situations applies to you is the first step toward resolving it.
The fault can stem from something as simple as a temporary software glitch or residual water in the drum, right through to a worn door lock assembly or a failing control board. Most cases are resolved without specialist tools.
Causes
- Temporary control board glitch — A brief power fluctuation or software error can cause the control board to lose track of the door lock's position. The lock itself may be perfectly functional, but the board fails to send or receive the correct signal to release it.
- Residual water in the drum — Bosch machines are designed to keep the door locked when water remains inside as a flood-prevention measure. If the drain cycle did not complete fully, the pressure sensor or float switch will prevent the door from unlocking until the drum is empty.
- Faulty or worn door lock assembly — The door interlock contains a bi-metallic strip or solenoid that physically moves a latch. Over time this component wears out, jams, or burns out, preventing it from moving to the unlocked position even when instructed to do so.
- Damaged door latch or striker — The plastic latch on the door itself, or the metal striker on the machine body, can crack or deform — particularly after a forceful close. A misaligned or broken latch can bind the lock mechanism so it cannot retract.
- Wiring fault between door lock and control board — The wiring harness connecting the door lock assembly to the main control board can develop a loose connector, chafed wire, or broken terminal. This interrupts the signal that confirms the lock has released, triggering E42.
- Control board failure — In less common cases, the main PCB itself is at fault — it may fail to output the voltage needed to actuate the lock solenoid. This is usually indicated when all other components test as healthy.
Step-by-Step Fix
- 1
Power cycle the machine
Turn the machine off using the power button, then switch it off at the wall socket. Leave it unplugged for at least 5 minutes to allow the control board capacitors to fully discharge. Plug back in, power on, and check whether the door releases and the error clears.
- 2
Check for water in the drum
Look through the door glass for standing water. If water is present, select a Drain or Spin programme to empty the drum. Once the drum is empty, the machine should automatically attempt to unlock the door. If the drain programme also fails, check the pump filter first (see step 3).
- 3
Clean the pump filter
Locate the filter access panel at the bottom front of the machine. Place a shallow tray and towels underneath, then slowly unscrew the filter cap to release any trapped water. Remove the filter, clear any debris such as coins, lint, or small garments, then refit it securely. A blocked filter can prevent draining, which in turn keeps the door locked.
- 4
Use the emergency door release
If the door remains locked after draining, look inside the filter access panel for a small coloured tab or cord — this is the manual door release. Pull it firmly downward or toward you (refer to your model's manual for the exact direction). This mechanically disengages the lock and allows you to open the door safely without forcing it.
- 5
Inspect the door latch and striker
With the door open, examine the plastic latch on the door and the metal striker plate on the machine body. Look for cracks, chips, or visible deformation. Gently test that the latch moves freely. A damaged latch or striker is a straightforward part replacement that does not require dismantling the machine beyond removing a few screws.
- 6
Test and replace the door lock assembly
If the latch and striker look intact, the interlock unit itself is the most likely culprit. Disconnect the machine from power, remove the door seal retaining band, and unclip the lock assembly from inside the front panel. Disconnect the wiring connector and check for burnt contacts or corrosion. A replacement interlock for most Bosch models is widely available and fits with basic screwdrivers.
- 7
Check the wiring harness
Before concluding the control board is at fault, trace the wiring from the door lock connector back toward the control board. Look for any pinched, chafed, or disconnected wires. Reseat any loose connectors firmly. A wiring fault is far cheaper to fix than a PCB and is worth ruling out completely before proceeding further.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If you have worked through all the steps above — power cycled the machine, confirmed the drum is empty, inspected the latch, replaced the door lock assembly, and checked the wiring — and the E42 error still returns, the fault is most likely within the main control board. PCB diagnosis and replacement requires specialist equipment to test output voltages safely and is not a practical DIY repair.
You should also call a service technician if the door lock assembly shows signs of burning or melting, if you are uncomfortable working with the internal wiring, or if the machine is still under warranty and you do not want to risk voiding it by dismantling components yourself.
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Frequently Asked Questions
Is it safe to force the door open when E42 is showing?
No — forcing the door can crack the latch, damage the door seal, or break the interlock housing, turning a simple repair into a more expensive one. Always use the manual emergency release cord located behind the filter access panel at the bottom of the machine. This is designed specifically for situations where the door will not open normally.
Can E42 appear even if the door lock is brand new?
Yes, it can. A new lock fitted with a damaged wiring connector, or installed while the control board has an underlying fault, will still trigger E42. If the error returns shortly after fitting a replacement interlock, check the wiring harness connections and consider having the control board tested by a service technician.
How long does a Bosch door lock assembly typically last?
Under normal use a door interlock should last between 7 and 10 years, though this varies with usage frequency and how gently the door is closed. Machines used multiple times daily, or in households where the door is regularly closed firmly, may see the component wear sooner.
Will E42 clear itself, or does it need to be manually reset?
In some cases — particularly when the fault is a temporary control board glitch — E42 will clear after a power cycle without any further action. However, if the underlying cause is a mechanical or electrical fault, the error will return at the end of the next cycle. A persistent E42 always points to a component that needs attention.
My machine shows E42 but the door actually opens fine — is that normal?
This can happen when the door lock position sensor sends an inconsistent signal to the control board, even though the mechanism itself moves correctly. It may indicate a loose wiring connector at the interlock or a sensor within the lock assembly that is beginning to fail. It is worth inspecting the connector and reseating it before replacing the whole unit.