This Detroit coolant sensor plausibility reference documents fault code SPN 110/FMI 2 (Coolant Outlet Temperature Not Plausible) for Detroit DD-series engines with paired coolant sensors. It reproduces the original TruckFaultCodes.com fault tree, from the first check through the final repair, so the code can be confirmed and worked in the exact order the factory intended. Each step lists the measured value or check and the pass or fail branch that follows, matching the layout used in the source document.
Detroit coolant sensor plausibility troubleshooting overview
The plausibility check compares the coolant inlet and outlet sensors under defined enabling conditions. It has the technician repair any cooling-system issue, bring the engine to 85°C (185°F), confirm thermostat operation, then inspect both sensor connectors and measure sensor resistance against the specification chart, replacing any sensor out of range. Follow the checks in sequence and verify the repair before clearing the code and releasing the vehicle.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD-series engines with paired coolant sensors |
| System / group | DTCs — coolant inlet and outlet temperature sensors |
| Fault code | SPN 110/FMI 2 |
| Source publication | TruckFaultCodes.com (© 2017) |
| Pages | 2 |
| File size | 0.4 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification — SPN 110/FMI 2
- Enabling conditions (500–2500 rpm, coolant above 65°C, over 11 V, 60 s)
- Cooling-system issue check
- Warm-up to operating temperature 85°C (185°F)
- Thermostat service and sensor-resistance check against the chart
Applicable truck models
It applies to Detroit DD-series engines using paired coolant inlet and outlet temperature sensors. Always cross-check the reading against any companion codes before condemning a component. For the official product and service literature, visit the Detroit Diesel website.
Who needs this Detroit coolant sensor plausibility manual
Mechanics resolving an implausible coolant reading who need the enabling conditions and the resistance-chart step. It is written for shop use as a quick, printable reference to keep beside a diesel diagnostic tool during the job.
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