This Detroit coolant level fault reference documents fault code SPN 111/FMI 1 (Coolant Level Low) for Detroit DD-series engines, including EPA10 models. 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 level fault troubleshooting overview
The fault tree opens by confirming whether the truck is an EPA10 model and whether the MCM, ACM and CPC software is at 7.6/8.6/R22 or higher. It then checks for companion codes, verifies the reservoir coolant level, and finishes with a six-point coolant-leak inspection. If the reservoir level is within limit, the guide directs replacing the engine coolant level sensor. 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, including EPA10 models |
| System / group | DTCs — engine coolant level sensor circuit |
| Fault code | SPN 111/FMI 1 |
| Source publication | TruckFaultCodes.com (© 2017) |
| Pages | 2 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification — SPN 111/FMI 1
- EPA10 software-level verification (MCM, ACM, CPC at 7.6/8.6/R22)
- Check for additional active fault codes
- Inspect coolant level in the reservoir
- Coolant-leak checks: head and air-compressor gaskets, hoses, coolant in oil, radiator cap, cab heater
Applicable truck models
This document applies to Detroit DD-series engines built to EPA 2007 and later standards, with a dedicated branch for EPA10 trucks. The SPN 111/FMI 1 procedure is referenced across the DD platform. 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 level fault manual
Fleet technicians and workshop owners who see a low-coolant warning and need the factory step order to separate a genuine leak from a failed level sensor. 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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