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SPN 629 FMI 2

Controller #1 — Data erratic, intermittent, or incorrect.
The signal jumps around, drops in and out, or disagrees with other information the controller has.

What the SPN covers: The engine controller itself has detected an internal problem. More on SPN 629.

What FMI 2 usually points to: Loose or corroded connectors, chafed wiring, a failing sensor, or two redundant sensors that do not agree. More on FMI 2.

Severity

HIGH — limit use, diagnose now

Can range from minor to no-start. Check power and grounds before blaming the ECM.

Likely causes

  1. Internal ECM fault
  2. Corrupted or interrupted programming
  3. Poor power or ground supply
  4. Water intrusion

Checks & fixes (easiest first)

  1. Check ECM power and ground
  2. Check for software updates or a failed reflash
  3. Inspect connectors for water

FAQ

What does SPN 629 FMI 2 mean?

Controller #1 — data erratic, intermittent, or incorrect. The signal jumps around, drops in and out, or disagrees with other information the controller has.

Is SPN 629 FMI 2 serious?

Can range from minor to no-start. Check power and grounds before blaming the ECM.

What should I check first for SPN 629 FMI 2?

Check ECM power and ground; Check for software updates or a failed reflash; Inspect connectors for water.