SPN 627
CAUTION
ECU power supply
The truck's control module (ECU) reports a fault on: ECU power supply.
SPN 627 means a truck control module (ECU) flagged a fault on ECU power supply, part of the Electrical / J1939 system on heavy-duty diesel trucks. DERATE rates it CAUTION: you can keep driving carefully, but get it checked soon. Part usually replaced: ECM power / ground circuit repair, $40–$500 (aftermarket to dealer) plus 1.5–4 h labor.
Electrical / J1939
Can I keep driving?
Yes, carefully. It does not usually cut power, but get it checked soon.
Part usually replaced
ECM power / ground circuit repair
$40–$500 (aftermarket to dealer)
Labor: 1.5–4 h
Fuses, relays and grounds before replacing the ECM
USD, part only. Labor is billed at the shop's hourly rate.
Data: DERATE verified base, updated October 2026
Related codes
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DERATE assists. It does not replace inspection by a qualified technician.