This Detroit turbo speed plausibility reference documents fault code SPN 103/FMI 2 (Turbocharger Speed Not Plausible) for Detroit DD13, DD15 and DD16 engines. 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 turbo speed plausibility troubleshooting overview
The plausibility tree first inspects the air-intake system, then the EGR system and valve for leaks or a broken butterfly. It follows with a road test that logs temperatures, engine and road speed, torque, manifold and boost. If the readings pass specification the Turbocharger Speed Sensor is replaced; otherwise the log is retained for support. 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 DD13, DD15 and DD16 engines |
| System / group | DTCs — turbocharger speed sensor (TSS) and EGR |
| Fault code | SPN 103/FMI 2 |
| Source publication | TruckFaultCodes.com (© 2017) |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification — SPN 103/FMI 2
- Air-intake leak and restriction inspection (filter and CAC)
- EGR system leak and damage inspection
- EGR valve butterfly damage check
- Road test with mechanical-panel log; replace TSS or contact support
Applicable truck models
It applies to Detroit DD13, DD15 and DD16 engines on the GHG14 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 turbo speed plausibility manual
Mechanics who need to separate an EGR fault from a genuine TSS failure before replacing parts. It is written for shop use as a quick, printable reference to keep beside a diesel diagnostic tool during the job.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download.
Related manuals library
