AEG C3 fault codewhat it means and how to fix it
Two different things share this label. Selected from the cleaning menu it is a three-hour clean. Shown on the display as Err C3, it means the door is not closed.
Before you start
What C3 means
Before anything else, work out which C3 you are looking at, because AEG use the same string for two unrelated purposes on the same appliance and no manufacturer page anywhere acknowledges the clash. In the pyrolytic cleaning menu of the manuals that use these names, C1, C2 and C3 are the three cycle lengths: light cleaning at one hour, normal at an hour and a half, and C3 thorough cleaning at up to three hours (three in most AEG manuals, two and a half in at least one).
Choosing C3 there is a normal thing to do and nothing is wrong. The fault is the other one, and on the manuals that use the longer form it is printed as Err C3. That means the oven will not start the cycle because the door is not closed.
AEG’s support site drops the Err prefix entirely, which is what makes the two collide. Assuming you have the fault rather than the menu option: the cavity reaches close to 500°C during a pyrolytic clean, so the oven locks the door and refuses to begin until it is satisfied the door is properly shut. AEG describe the trigger as the door being open "or slightly open", and slightly is the operative word — a door that looks closed can sit a few millimetres off the catch.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| The door is genuinely not latched | Pushed to rather than closed. An oven door is heavy enough to swing back a fraction after you let go of it, and it will sit there looking shut. | Common |
| Something in the cavity is holding it fractionally open | A shelf not pushed fully home, or a roasting tin left standing proud, will stop the door seating without being obvious from the front. | Common |
| The door seal has perished or lifted out of its channel | The rope seal around the cavity flattens with age and can pull free at a corner, which leaves the door resting on the seal rather than closing onto it. | Occasional |
| The door lock itself is defective | AEG raise this in the manual rather than on the website: their troubleshooting table gives the cause as the door not being fully closed or the lock being faulty. | Occasional |
What to try yourself
Open the door fully and close it again deliberately, with a hand on it until you feel it take. Do not swing it.
Take everything out of the cavity — shelves, trays, the grill pan — and try again. This also clears C1 if the rails were the real problem.
Run a finger round the door seal and check it is sitting in its channel the whole way round, with no corner lifted or flattened.
Start the pyrolytic programme again. If C3 clears, that was it. If it returns with the door plainly shut, stop and read the F1 page instead.
Get a qualified appliance engineer to look at your AEG C3
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified appliance engineer, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
What it costs to fix
Typical repair cost
Depends on the cause
Time on site
5 minutes
Nothing, unless the door seal has gone. A replacement AEG oven door seal is typically £15 to £40 and is usually a clip-in part.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related AEG fault codes
- C1Usually simple to fixCheck first whether you picked C1 off the cleaning menu, where it is the one-hour light clean. As a fault it means the telescopic rails are still in the oven.Related: pyrolytic cleaning
- PYRUsually simple to fixA reminder to run a self-clean, not a fault. The important part: the oven is counting hours rather than detecting dirt, so a spotless oven will still ask.Related: pyrolytic cleaning
- C2Usually simple to fixAs a fault, the food probe is still in the oven and the pyrolytic cycle will not run. As a menu choice, C2 is simply the 90-minute normal clean.Related: pyrolytic cleaning
- C4Usually simple to fixA steam function is switched on and it blocks the pyrolytic cycle. The catch is that AEG give the button two different names on the same support page.Related: pyrolytic cleaning
- F1Get it checkedOne code, two published meanings. On a pyrolytic AEG oven it is about the door not closing. On a non-pyrolytic one AEG call it an electronic fault and send you straight to service.Related: same brand
- DemoUsually simple to fixThe oven lights up, accepts settings and never heats. AEG admit demo mode can switch itself on after a power cut, and the code to switch it off is 2 4 6 8.Related: same brand
Own an AEG oven? Save it and its codes come first next time.
Related guides
Common questions about AEG C3
I chose C3 for a long clean and the oven is running. Is that a fault?
No, and this is the confusion worth clearing up. On AEG ovens that name their cleaning cycles this way, C3 is thorough cleaning and runs for up to three hours. If you selected it and the cycle started, the oven is doing exactly what you asked. The fault version is the one the oven puts on the display by itself, written as Err C3 in the manuals that use the longer form.
Why does AEG use the same code for two different things?
We do not know, and no AEG document we found acknowledges the overlap. The manual disambiguates by printing the fault as Err C3 while the cleaning option stays plain C3, but AEG’s own support website drops the Err prefix and refers to the fault as C3. That leaves the website contradicting the manual on the same appliance.
Why does the door need to be locked at all?
Because of the temperature. AEG put it at approximately 500°C inside the cavity during a pyrolytic clean, which is roughly twice a normal roasting temperature and hot enough to make opening the door genuinely dangerous. The lock is not the oven being awkward, and it is not something to defeat.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer support portal
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.