Home › Codes › SPN 1761 › FMI 1

SPN 1761 FMI 1

Aftertreatment 1 DEF Tank Volume — Value too low (most severe).
The reading is valid but far below the normal operating range, at the most serious 'too low' level.

What the SPN covers: How full the diesel exhaust fluid (DEF) tank is. More on SPN 1761.

What FMI 1 usually points to: A real under-condition such as very low oil pressure or low fuel pressure, or a sensor that has drifted low. More on FMI 1.

Severity

MEDIUM — fix soon

Running low on DEF leads to inducement derates and eventually a speed limit. Fill up.

Likely causes

  1. Low DEF level
  2. Frozen DEF
  3. Faulty level sensor (often combined with temperature/quality sensor)
  4. Wiring fault

Checks & fixes (easiest first)

  1. Fill the tank with fresh, certified DEF
  2. Check the tank sender for crystal buildup
  3. Compare gauge with a visual check

FAQ

What does SPN 1761 FMI 1 mean?

Aftertreatment 1 DEF Tank Volume — value too low (most severe). The reading is valid but far below the normal operating range, at the most serious 'too low' level.

Is SPN 1761 FMI 1 serious?

Running low on DEF leads to inducement derates and eventually a speed limit. Fill up.

What should I check first for SPN 1761 FMI 1?

Fill the tank with fresh, certified DEF; Check the tank sender for crystal buildup; Compare gauge with a visual check.