SPN 620
CAUTION
5V sensor supply
The truck's control module (ECU) reports a fault on: 5V sensor supply.
SPN 620 means a truck control module (ECU) flagged a fault on 5V sensor 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: Sensor supply wiring / harness repair, $40–$400 (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.
Most likely causes
Shorted sensor pulling supply down
Chafed harness
Recommended tests
1. Unplug sensors one at a time and watch 5V return
Part usually replaced
Sensor supply wiring / harness repair
$40–$400 (aftermarket to dealer)
Labor: 1.5–4 h
Usually a wiring repair, not a part
USD, part only. Labor is billed at the shop's hourly rate.
Data: DERATE verified base, updated October 2026
Related codes
Read it off your own dash
Take one photo and DERATE tells you whether you can keep driving.
Ask DERATE
DERATE assists. It does not replace inspection by a qualified technician.