SPN 520 — Actual Retarder – Percent Torque
System: Retarder / Engine brake
How much braking torque the retarder or engine brake is actually producing, as a percentage.
Can I keep running it?
MEDIUM — fix soon
Your engine brake or retarder may not work. Drive with extra caution on grades.
Likely causes
- Retarder or engine brake control problem
- Network message missing or invalid
- Faulty retarder module or sensor
Checks & fixes (easiest first)
- Check retarder/engine brake operation and switch inputs
- Check for J1939 network codes
- Check codes in the retarder or transmission module
Common FMIs with SPN 520
- SPN 520 FMI 2Data erratic, intermittent, or incorrect
- SPN 520 FMI 9Abnormal update rate
- SPN 520 FMI 19Received network data in error
Related codes
- SPN 639J1939 Network #1 (Primary Data Link)
FAQ
What does SPN 520 mean?
SPN 520 is Actual Retarder – Percent Torque. How much braking torque the retarder or engine brake is actually producing, as a percentage.
Can I keep running with SPN 520?
Your engine brake or retarder may not work. Drive with extra caution on grades.
What causes SPN 520?
Retarder or engine brake control problem; Network message missing or invalid; Faulty retarder module or sensor.