Code Details
| Display code | Navistar Aware SPN 841 FMI 2 |
|---|---|
| SPN | 841 |
| FMI | 2 |
| OEM code | Navistar / International Aware SPN 841 FMI 2 |
| Manufacturer | Navistar / International |
| System | Aware Vehicle Intelligence / Telematics |
| Component | GPS module — no satellite signal |
| 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 Aware module's GPS receiver is functioning — it is not showing a device failure — but it has been unable to acquire or maintain a satellite fix for 5 minutes. This is a coverage or installation condition rather than a module hardware fault. GPS signals can be blocked or degraded by metal rooflines, tunnels, dense urban canyons, bad antenna installation, or interference.
Navistar S08312 maps Navistar Aware SPN 841 FMI 2 to GPS Module — data erratic, intermittent or incorrect. The qualifying condition is no GPS satellite signal for more than 5 minutes when no GPS hardware fault (FMI 12) is also active. This distinguishes between a signal absence (FMI 2) and a module failure (FMI 12).
Common Symptoms
- Fleet portal shows vehicle location as unknown, stale, or missing
- Aware module GPS position data is unavailable in J1939 output or fleet reporting
- Fault may clear automatically once the vehicle is in a clear-sky environment
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- GPS antenna mounted in a location with poor sky view — under a metal roof overhang, behind a metal support beam, or partially blocked by the sleeper box
- GPS antenna cable damaged, disconnected, or with a connector that has developed high resistance
- Vehicle operating continuously in GPS-denied environments (underground facilities, warehouse docks, covered areas)
- GPS antenna failed internally while the module-to-antenna connection is still intact — no FMI 12 because the module communicates with the antenna, but the antenna cannot receive satellites
First Checks
- Note where the vehicle has been operating — sustained operation in covered environments (loading docks, tunnels, buildings) is the simplest explanation.
- Check whether the fault clears when the vehicle is parked in an open outdoor location with a clear sky view.
- Inspect the GPS antenna mounting location and cable for damage, disconnection, or routing issues that could block signal or cause signal loss.
- If the fault persists outdoors with a clear sky, use Navistar diagnostic software to verify the GPS module is receiving antenna power and check the antenna connection at the module.
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
How long does the vehicle need to be stationary outdoors to clear Navistar Aware SPN 841 FMI 2?
The fault clears when the GPS module receives a valid satellite fix. In a clear outdoor environment, a cold start acquisition typically takes 1–5 minutes. If the fault does not clear after 10 minutes of outdoor operation in a clear location, investigate the antenna installation.
Can Navistar Aware SPN 841 FMI 2 cause mileage reporting errors in the fleet portal?
Yes. GPS-derived mileage and distance calculations stop updating when no satellite fix is available. In most fleet systems, odometer data from J1939 continues independently, but GPS-based position tracking and the associated route mileage are unavailable while Navistar Aware SPN 841 FMI 2 is active.
What is the difference between Navistar Aware SPN 841 FMI 2 and SPN 841 FMI 12?
FMI 2 means the GPS module is functional but has no satellite signal — a coverage or antenna issue. FMI 12 means the Aware module cannot communicate with the GPS device at all, or the device reported an internal failure — a hardware failure in the antenna or module. FMI 2 often clears by moving outdoors; FMI 12 typically requires hardware inspection or replacement.