Code Details
| Display code | Navistar Aware SPN 251 FMI 13 |
|---|---|
| SPN | 251 |
| FMI | 13 |
| OEM code | Navistar / International Aware SPN 251 FMI 13 |
| Manufacturer | Navistar / International |
| System | Aware Vehicle Intelligence / Telematics |
| Component | RTC module — out of calibration |
| Source address | Unknown or not applicable |
| Severity | low |
| Review status | ai source checked |
| Source confidence | high |
| Last reviewed | 2026-03-26 |
Plain-English Meaning
The RTC inside the Aware module provides the timestamp reference for all logged events. FMI 13 means the RTC's current time differs from accurate UTC time by more than 10 minutes. This can occur after an extended power loss, after an RTC backup battery failure, or if the module has not been able to synchronize its time with a GPS-derived UTC reference.
Navistar S08312 maps Navistar Aware SPN 251 FMI 13 to RTC Module — out of calibration. The fault activates when the RTC time is out of date by more than 10 minutes. This is the calibration threshold for the RTC's time accuracy requirement.
Common Symptoms
- Event timestamps in the fleet portal are off by more than 10 minutes
- Fault may appear after the vehicle has been parked for an extended period without power
- Fleet events may sort into the wrong day or trip window until time is resynchronized
- The condition may clear after GPS time becomes available but return after the next extended power-off period
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- RTC backup battery depleted, causing the RTC to lose its time setting during power-off
- GPS time synchronization not available to update the RTC — no GPS fix or J1939 time source
- Module had no power for an extended period and the RTC reset to a default or incorrect time
First Checks
- Allow the vehicle to operate in a GPS-visible location — the Aware module may synchronize the RTC from GPS time and clear the fault.
- If GPS time sync resolves the fault, the issue was the RTC drifting during power-off. Check the RTC backup battery condition.
- Compare the module time, GPS time, and fleet portal event time so the shop can tell whether the error is local to the module or introduced during data upload.
- Review recent battery disconnects, dead-battery events, or long storage periods that could explain why the clock drifted.
- If the fault persists after GPS synchronization, the RTC may have a deeper calibration issue requiring service.
Can I Keep Driving?
Severity depends on active status, warning lamps, affected system, and related codes. Stop safely for red stop lamps, brake warnings, oil pressure warnings, high coolant temperature warnings, severe derate, or any abnormal vehicle-control concern.
Related Lookup Pages
Sources
- Navistar Aware Vehicle Intelligence Diagnostic Trouble Codes S08312 Navistar / International Truck Body Builder · oem · accessed 2026-05-05 · confidence high
Source: Navistar / International Truck Body Builder, Navistar Aware Vehicle Intelligence Diagnostic Trouble Codes S08312. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - Navistar Engine Diagnostic Trouble Code Body Builder References Navistar / International Truck Body Builder · oem · accessed 2026-05-05 · confidence medium
Source: Navistar / International Truck Body Builder, Navistar Engine Diagnostic Trouble Code Body Builder References. This page paraphrases factual fields only and is not a substitute for the original document.
Open source
FAQ
Does the Aware module automatically correct the RTC from GPS time?
Many Aware module implementations use GPS-derived UTC time to discipline the RTC. If the GPS module is functioning and has a valid satellite fix, the Aware module typically synchronizes the RTC automatically. Driving in a GPS-available area will often clear this fault without manual intervention.
Can this fault cause HOS record timestamps to be wrong?
The Aware module's timestamps are used for fleet telematics reporting. If the Aware module is also serving as an ELD, incorrect timestamps would directly affect HOS record accuracy. If the Aware system is used only for fleet visibility (not as an ELD), the impact is on reporting accuracy.
How quickly does the RTC drift if the backup battery is depleted?
Without a backup battery, the RTC typically loses its time setting immediately when vehicle power is removed. On the next power-up, it starts from a default or stored last-known time, which may be significantly incorrect if the vehicle was parked for days or weeks.