This DEF metering temperature sensor sheet documents Detroit fault code SPN 4337 / FMI 3 on EPA10 engines, a temperature drift condition. The procedure combines a resistance range check with voltage measurements to isolate a drifted sensor from a shorted or open wire.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD-Series (DD13, DD15, DD16) and Series 60 (DDEC VI) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 4337 / FMI 3 |
| Fault name | DEF metering unit temperature – drift |
| Emissions platform | EPA10 |
| Pages | 2 |
| File size | 0.3 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com (© 2017); Detroit Power Service Literature |
DEF metering temperature sensor sections covered
The two-page routine first checks the sensor for a resistance fault, then reads harness voltage at two pins to find shorts or opens.
- Fault code header: SPN 4337, FMI 3 (temperature drift)
- Disconnect the sensor connector and inspect for bent or corroded pins
- Measure resistance between pin 1 and pin 2 of the connector
- Read voltage at pin 2 to ground (2.75 to 3 volts)
- Read voltage at pin 1 to find a short or open to ACM2 pin 86
- Repair the harness, or replace the sensor per Power Service Literature
Applicable truck models
This procedure covers Detroit DD-Series (DD13, DD15 and DD16) and Series 60 DDEC VI engines on the EPA10 platform using the ACM2 control module. The “Removal of the Diesel Exhaust Fluid Temperature Sensor” chapter in Detroit Power Service Literature is reached through the Detroit Diesel official website.
Who needs this DEF metering temperature sensor manual
Technicians facing an intermittent SPN 4337 / FMI 3 need this metering temperature sensor manual, because a drift fault demands the exact voltage windows and pin map rather than a straight resistance reading.
The full 2-page PDF is available in the DiagTechPro manuals library; a free account is required to download. For workshop reference, Detroit documents the matching component removal and installation steps for SPN 4337 / FMI 3 in Power Service Literature, and technicians should keep the wiring pin numbers shown in this sheet on hand while testing on the bench.
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