SPN 5360 FMI 18 is the Detroit DD Series fault code for Cylinder #3 Engine Smoothness Control / Quantity Excess, and this diagnostic sheet lists the description, enabling conditions and step-by-step troubleshooting. Published on TruckFaultCodes.com (Copyright 2017), it explains that the MCM2.1 has driven the injector pulse to its maximum value while trying to smooth idle on cylinder #3.
Official document details
| Brand | Detroit |
| Model coverage | DD13, DD15, DD16 (DD Series, EPA 2007-Current) and Series 60 DDEC VI |
| System/Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 5360 FMI 18 |
| Source | TruckFaultCodes.com, Copyright 2017 |
| Pages | 3 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code description (SPN and FMI)
- Monitored parameter and enabling conditions
- Dash lamps (MIL and CEL) and engine reaction
- Entry conditions for the code
- Possible causes (cylinder kit, valve train, injector)
- Troubleshooting steps 1 to 5
Applicable truck models
This fault sheet applies to Detroit DD13, DD15 and DD16 engines in the DD Series (EPA 2007-Current) range, and the same SPN/FMI logic is referenced for the Series 60 DDEC VI platform. All removals assume a Three-Filter fuel system. For OEM-level service literature and engine coverage, see the official Detroit Diesel website.
SPN 5360 FMI 18 troubleshooting steps
After confirming the code with the diesel diagnostic tool, Step 1 checks for multiple codes and services any others first. Step 2 runs the relative cylinder compression test; if cylinder #3 reads low compression the failure is mechanical. If all cylinders are within 10%, Step 3 brings the engine above 60°C (140°F), then Step 4 reads the Idle Speed Balance (ISB) value for cylinder #3 — a value pinned at the +100 limit points to a fueling fault. Step 5 inspects the fuel line from rail to injector; when damage is found the high pressure fuel injector lines are replaced, otherwise the fuel injector itself is replaced. The document notes MIL and CEL illuminate and a 25% engine derate accompany this code.
Who needs this 5360 FMI 18 manual
Heavy-duty diesel technicians and DD Series fleet owners chasing a rough-idle or single-cylinder power complaint use this 5360 FMI 18 manual to decide whether the root cause is mechanical compression loss or a fueling fault before replacing any parts.
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