Dishwasher
E12
The E12 error code on an AEG dishwasher indicates a problem with the water heating system — specifically that the water isn’t reaching the required temperature within the expected time. It’s a moderately serious fault that will stop your dishwasher from completing a wash cycle, but it’s often fixable without a call-out.
What does this error mean?
Your AEG dishwasher continuously monitors water temperature during a cycle. The E12 code means the control board has detected that the water either isn’t heating up at all, or is heating far too slowly — taking longer than the programmed threshold allows. This is most commonly a fault with the heating element or its associated components, rather than a problem with the water supply itself.
Est. repair cost
£80–£140 professional repair; £20–£45 DIY part (heating element or NTC sensor)
🔍 Likely causes
🛠️ Step-by-step fix
Run a hard reset first: switch the dishwasher off at the wall socket, wait 5 minutes, then power it back on and start a short cycle. A temporary sensor glitch can trigger E12 and a reset clears it.
Check and clean the filter assembly: remove the cylindrical filter and flat mesh filter from the base of the dishwasher tub, rinse under hot water, and use a soft brush to remove debris. A blocked filter strains the pump and can indirectly affect heating performance.
Run a descaling cycle: if you’re in a hard-water area (much of southern England, for example), pour a dishwasher descaler such as Finish Dishwasher Cleaner directly into the empty tub and run a hot cycle at 65°C or higher. Limescale on the element is a very common cause of E12.
Inspect the spray arms: remove the upper and lower spray arms by unscrewing or unclipping them, and clear any blocked nozzles with a cocktail stick. Blocked arms reduce water circulation over the heating element.
Check the heating element visually: remove the lower basket and look at the exposed element at the base of the tub. If you can see visible cracks, burn marks, or heavy corrosion, the element has failed and needs replacing. This part replacement is DIY-safe if you’re comfortable disconnecting and reconnecting spade connectors — source the correct AEG part by model number.
Test the NTC sensor with a multimeter (optional, intermediate DIY): disconnect the sensor from its connector and measure resistance — a healthy AEG NTC sensor typically reads around 10kΩ at room temperature. A reading of zero or infinity indicates a failed sensor needing replacement.
📞 When to call a professional
If a full descale and reset don’t clear the E12 code, and you’re not confident testing or replacing internal components, call an appliance repair engineer. Tell them: ‘My AEG dishwasher is showing an E12 error — I suspect a heating element or NTC sensor fault.’ If the control board is implicated, that diagnosis and replacement should always be handled by a qualified engineer, as incorrect board installation can cause further electrical damage.
⚖️ Repair or replace?
A heating element replacement in the UK typically costs £80–£140 fitted by an engineer, or £20–£45 if you source the part yourself and fit it. If your machine is under 7 years old and otherwise reliable, repair is almost always worth it. For machines aged 10 years or more with multiple faults, replacement with a new AEG or equivalent dishwasher (from around £350) is likely the better long-term value.