SPN 1636 FMI 2 is the Detroit engine air temperature plausibility code, a fault out of range (low box), and this sheet gives the voltage checks and Motor Control Module (MCM) pin targets that isolate it. Work it before replacing the pressure/temperature sensor.
Official document details
| Brand | Detroit |
| Model coverage | DD13, DD15, DD16 (EPA 2007-current) |
| System / group | Intake air management — manifold temperature |
| Fault code | SPN 1636 / FMI 2 |
| Publication no. | Not printed on sheet |
| Year / revision | Reference dated 2017 |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault header: SPN 1636 / FMI 2 — engine air temperature plausibility fault out of range
- Monitored parameters and 25% derate reaction
- Step 1-2 — connect tool, rule out EGR faults
- Step 3 — inspect and replace charge air outlet and intake manifold sensors
SPN 1636 FMI 2 troubleshooting steps
The monitored parameters are the intake manifold and charge air cooler outlet temperature sensors, checked once per drive cycle after a warm start with idle under 900 RPM and coolant over 65C. Step 1 connects the diesel diagnostic tool and Step 2 rules out any Exhaust Gas Recirculation (EGR) system faults first, since those skew the comparison. If none are present, Step 3 disconnects the charge air outlet and intake manifold temperature sensors, inspects the connectors for bent, spread or corroded pins, repairs any pin damage, and replaces both sensors. A 25% derate accompanies the code.
Applicable truck models
This procedure covers Detroit DD-series engines — DD13, DD15 and DD16 on the EPA 2007-current platform — and shares its SPN/FMI structure with related Series 60 DDEC VI applications. A 25% derate can accompany this code, so confirm the emissions calibration (EPA07, EPA10 or GHG14) before probing. For engine serial-number and calibration confirmation, use the Detroit Diesel official support site.
Who needs the SPN 1636 FMI 2 manual
Diesel technicians use this sheet to test the intake manifold pressure/temperature sensor circuit, read the MCM connector pins, and separate a wiring short or open from a failed sensor before parts are ordered.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download. Source: Detroit SPN/FMI fault-code reference (© 2017); voltages are read with the Detroit Diesel Diagnostic Link (DDDL) and a calibrated multimeter.
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