SPN 625 FMI 13 – ECAN ID_1629 Diagnostic Message Not Received this Ignition Cycle Fault Code (Symptoms, Causes & Fix)

Mar 12, 2026

The SPN 625 FMI 13 fault code indicates a communication error within the diesel engine's electronic control module (ECM) network. Specifically, it means that the ECM did not receive the expected ECAN ID_1629 diagnostic message during the current ignition cycle. This diagnostic trouble code suggests a disruption in the communication between modules, which can affect the engine's performance and diagnostic capabilities.

What SPN 625 FMI 13 Means

The SPN 625 FMI 13 fault code represents a failure in the ECM's ability to receive a specific diagnostic message, ECAN ID_1629, during the ignition cycle. This message is crucial for the ECM to monitor and control various engine functions. When this message is not received, it indicates a potential issue in the communication network, which could be due to wiring, connectors, or the ECM itself.

Common Causes of This Fault Code

Faulty or disconnected wiring harness
Defective ECM or module not sending/receiving data
Corroded or loose connectors
Faulty terminating resistor in the CAN network
Intermittent power supply to the ECM

Symptoms Drivers May Notice

When the SPN 625 FMI 13 fault code is active, drivers may notice symptoms such as erratic engine performance, warning lights on the dashboard, or a lack of response from certain electronic systems. In some cases, the engine may enter a derate mode to protect itself from potential damage.

How Technicians Diagnose This Fault

Diagnosing the SPN 625 FMI 13 fault code involves a systematic approach. Technicians should start with a visual inspection of the wiring harness and connectors for any signs of damage or corrosion. Next, they should use a multimeter to check for continuity and shorts in the CAN wiring. It's also important to verify the presence and condition of terminating resistors in the network. Using diagnostic software, technicians can monitor CAN bus traffic to identify missing messages and ensure the ECM is receiving power and ground properly.

Common Misdiagnosis

Technicians often misdiagnose this fault by assuming a faulty sensor without checking the communication network. Another common mistake is replacing the ECM prematurely without verifying power and ground connections. Overlooking intermittent wiring issues due to vibration or heat exposure is also a frequent error.

Can You Keep Driving?

While it may be possible to continue driving with the SPN 625 FMI 13 fault code active, it's not advisable. The communication error can lead to engine derate or protection mode, which can affect performance and potentially cause further damage if not addressed promptly.

Mechanic's Diagnostic Tip

When dealing with communication errors like SPN 625 FMI 13, always ensure that the CAN network's terminating resistors are intact and properly connected. This simple check can often resolve communication issues without unnecessary part replacements.

Frequently Asked Questions

Q: What does SPN 625 FMI 13 indicate?
A: It indicates a communication error where the ECM did not receive the ECAN ID_1629 message during the ignition cycle.

Q: Can a faulty ECM cause this fault code?
A: Yes, a defective ECM can be a cause, but it's important to rule out wiring and connector issues first.

Q: Is it safe to drive with this fault code?
A: Driving with this fault code is not recommended as it may lead to engine derate or protection mode, affecting performance.