SPN 441
INFO
Auxiliary temperature
The truck's control module (ECU) reports a fault on: Auxiliary temperature.
SPN 441 means a truck control module (ECU) flagged a fault on auxiliary temperature, part of the Auxiliary system on heavy-duty diesel trucks. DERATE rates it INFO: it does not limit driving; have it checked at the next service. Confirm with tests before replacing parts.
Auxiliary
Can I keep driving?
Yes. It is informational and does not limit driving; have it checked at the next service.
Data: DERATE verified base, updated October 2026
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