Prusa Error 13308: Nozzle Heater Overcurrent
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Prusa error 13308 means the board measured too much current flowing through the nozzle heater and cut the power. This is an electrical fault, not a temperature one — no amount of changing temperature settings will affect it. The usual causes are a chafed heater lead at the print head, a shorted cartridge, or the wrong heater fitted.
It is worth being clear about the difference. A preheat error means the hotend did not get hot enough. An overcurrent error means the heater circuit is drawing more than it should, which is a wiring or component fault and potentially a dangerous one.
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Check in this order, with the printer unplugged
- The heater lead at the head. It flexes on every layer. Look for worn insulation, especially where the bundle enters the print head and at the tightest curve of the loom.
- Measure the cartridge. Cold, across its two terminals. A 24 V 40 W heater should read around 14–15 ohms. Far below that means an internal short and it needs replacing.
- Check which heater is fitted. A lower-resistance cartridge draws more current than the board allows. This bites after a third-party hotend swap — see what a hotend swap changes for the general case.
- Inspect the connector. A single stray strand bridging the pins does exactly what an internal short does.
Do not clear and retry repeatedly
The protection exists because an overcurrent condition in a heater circuit generates heat where you do not want it. Clearing the error and restarting a print without finding the cause is the one genuinely unsafe response to this code.
Related codes
13309 is overcurrent on the xBuddy input port, which is about accessories rather than the heater. 13202 is a preheat failure — thermal, not electrical. Background on what the heater and its cartridge actually do is in hotend anatomy.
The same error reads 12308 on MINI, 31308 on CORE One, 35308 on CORE One L, 16308 on iX and 23308 on MK3.5.
Prusa Error 13308 FAQ
Is error 13308 dangerous?
The condition it detects can be. The printer cutting power is the safe outcome. Find the short before running it again.
What resistance should the heater cartridge read?
Around 14–15 ohms for a 24 V 40 W cartridge. Much lower suggests an internal short; open circuit means a failed heater and a different error.
Can a third-party hotend cause this?
Yes, if its heater is a different wattage or voltage than the board expects. Match the original specification rather than assuming any cartridge fits.
Could it be the board rather than the heater?
Possible but uncommon. Rule out the cable, the cartridge and the connector first — those account for most cases.
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