This Detroit DEF temperature sensor sheet is the one-page troubleshooting guide for fault code SPN 4337 / FMI 4 on EPA10 engines, where the metering temperature sensor circuit has failed low. It lists the monitored parameter, the MIL and CEL lamp reaction, and a wire-versus-sensor resistance test.
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 4 |
| Fault name | DEF temperature sensor circuit failed low |
| Emissions platform | EPA10 |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com (© 2017); Detroit Power Service Literature |
Detroit DEF temperature sensor sections covered
The single page defines the enabling conditions and then runs a short circuit check between the sensor connector and the ACM2.
- Monitored parameter and enabling conditions (always enabled, 2 second duration)
- Dash lamps: MIL and CEL
- Disconnect the DEF metering temperature sensor connector
- Inspect the harness for bent, spread or corroded pins
- Measure resistance between pin 1 and ground (less than 1K ohms)
- Repair the wire to ACM2 pin 86, or replace the sensor
Applicable truck models
These steps suit Detroit DD-Series (DD13, DD15 and DD16) and Series 60 DDEC VI engines on the EPA10 aftertreatment platform using the ACM2 control module. Sensor removal follows the “Removal of the Diesel Exhaust Fluid Temperature Sensor” chapter in Detroit Power Service Literature at the Detroit Diesel official website.
Who needs this Detroit DEF temperature sensor manual
This DEF temperature sensor manual helps a workshop confirm SPN 4337 / FMI 4 quickly, telling the technician whether to repair the harness or replace the sensor. It removes the guesswork behind a failed-low reading.
The full 1-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 4 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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