What Does Error Code E90 Mean on a Siemens Washing Machine?
Perform a full power cycle by switching the machine off at the wall socket, waiting 5 minutes, then switching it back on and restarting the programme — this clears temporary software glitches and resolves the fault in many cases (takes about 5 minutes).
Fault description
Error code E90 points to a problem with the internal communication between components on your Siemens washing machine's main control board (PCB). The board manages every function of the machine — from motor speed and water intake to heating and spin cycles — so when its internal communication breaks down, the machine cannot operate safely and will stop mid-cycle or refuse to start.
When E90 appears, the machine typically halts the current programme and displays the code on the control panel. You may notice the drum has stopped moving, the door remains locked, or the display becomes unresponsive. In some cases the machine will restart briefly before the error reappears.
The good news is that E90 is sometimes caused by a temporary software glitch rather than a physical component failure, which means a straightforward reset can be enough to clear it. Working through the steps below in order will help you identify whether this is a simple fix or something that needs professional attention.
Causes
- Temporary software glitch on the control board — A brief power fluctuation, interrupted cycle, or software hiccup can cause the PCB to lose its internal communication state. This is the most common trigger and is often resolved by a full power cycle.
- Loose or corroded wiring harness connections — The ribbon cables and wiring connectors linking the main PCB to the display board or sub-boards can work loose over time due to vibration. Corrosion on connector pins can also interrupt the signal and trigger E90.
- Faulty or damaged main control board (PCB) — If the PCB itself has suffered component failure — such as a blown capacitor or damaged microprocessor — it will be unable to maintain internal communication. Physical damage from moisture ingress or power surges is a common cause.
- Faulty display or user interface board — The display module communicates constantly with the main PCB. If the interface board develops a fault, the main board may interpret the loss of communication as an E90 error even though the main PCB itself is undamaged.
- Power supply instability — An unstable mains supply, a failing suppressor filter on the board, or a worn power inlet component can cause the PCB to receive inconsistent voltage. This can corrupt the board's internal processes and trigger communication errors.
Step-by-Step Fix
- 1
Power cycle the machine
Turn the washing machine off using the power button, then switch it off at the wall socket. Leave it completely unplugged for at least 5 minutes to allow the capacitors on the board to fully discharge. Plug it back in, switch on at the wall, and attempt to start a new programme. This clears temporary software faults and resolves E90 in a significant number of cases.
- 2
Perform a factory reset
If the power cycle alone does not clear the code, try resetting the machine to its factory defaults. On most Siemens models this is done by turning the programme dial to the off position, then holding the Start/Pause button for around 5 seconds. Refer to your model's user manual for the exact reset procedure, as button combinations can vary between models.
- 3
Check the mains power supply
Plug another appliance into the same socket to confirm the outlet is delivering a stable supply. If you have a surge-protected extension lead, try connecting the washing machine directly to the wall socket instead, as some extension leads can cause voltage irregularities. A consistently unstable supply will cause the error to return even after a successful reset.
- 4
Inspect the wiring harness and connectors
Switch off and unplug the machine before opening the back or top panel (consult your model's service guide for access). Locate the ribbon cables and wiring connectors running between the main PCB and the display board. Press each connector firmly to reseat it, and look for any signs of corrosion, burn marks, or damaged insulation. Reconnect anything that appears loose, then reassemble and test.
- 5
Inspect the main PCB for visible damage
With the machine unplugged and the PCB accessible, examine the board carefully under good lighting. Look for swollen or leaking capacitors, scorch marks, or areas where moisture may have reached the board. Any visible damage to the board is a strong indicator that the PCB needs to be replaced rather than repaired.
- 6
Test or replace the display/interface board
If the main PCB looks undamaged, the fault may lie with the display or user interface board. If you have access to a compatible replacement board, swapping it out is a practical way to confirm whether this component is responsible. Ensure the machine is fully unplugged before handling any boards, and take note of all connector positions before disconnecting anything.
- 7
Replace the main control board (PCB)
If all other steps have been completed without resolving the fault, the main PCB is the most likely culprit. Source a compatible replacement board using your machine's full model number. Fitting a new PCB is a straightforward swap on most Siemens models, but if you are not confident working with electronics, this step is best handed to a service technician.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If the error code returns immediately after a power cycle and factory reset, and you have found no loose connections or visible damage, the main PCB has most likely suffered an internal component failure that cannot be resolved through DIY steps. Similarly, if you notice burn marks, a smell of burning plastic, or signs of moisture damage on the board, stop troubleshooting and contact a service technician — continuing to run the machine in this state carries a risk of further damage.
You should also call a service technician if the machine's display is completely unresponsive, if the door will not unlock after a power cycle, or if the error reappears within a few cycles of fitting a new display board. These symptoms suggest a deeper fault with the main PCB or the machine's internal wiring that requires specialist diagnostic equipment to trace accurately.
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Frequently Asked Questions
Will a power cycle always fix error E90 on a Siemens washing machine?
A power cycle fixes E90 when the cause is a temporary software glitch, which is the most common scenario. However, if the fault is caused by a damaged PCB, a faulty display board, or a wiring problem, the error will return after the reset. If E90 comes back within a few cycles, work through the remaining diagnostic steps to identify the underlying cause.
Is it safe to keep using my Siemens washing machine when E90 is showing?
No. When E90 is active, the machine has detected an internal communication fault and will typically stop the programme to prevent further damage. Attempting to force the machine to run through repeated resets without investigating the cause could worsen a developing PCB fault. It is best to diagnose and resolve the error before running a full wash cycle.
How much does it cost to replace a Siemens washing machine PCB?
Replacement main control boards for Siemens washing machines typically cost between £60 and £180 depending on the model, with older or less common models sometimes sitting at the higher end. If you fit the board yourself, that is your total cost. A service technician will add a labour charge on top, so it is worth confirming the total quote before proceeding.
Can a power surge cause error E90?
Yes. A sudden power surge can corrupt the software state on the PCB or physically damage components on the board, both of which can trigger E90. If the error appeared immediately after a power cut or electrical storm, inspect the board carefully for burn marks or damaged components. Using a surge-protected socket can help prevent this type of fault in future.
How do I find the right replacement PCB for my Siemens washing machine?
Locate the full model number on the rating plate, which is usually found on the inside of the door frame or on the back of the machine. Use this number — not just the series name — when searching for a replacement board, as PCBs are often model-specific. Cross-reference the part number printed on the existing board if possible to confirm compatibility before purchasing.