This DEF pressure sensor fault sheet documents Detroit code SPN 4334 / FMI 3 on GHG14 engines, a circuit-failed-high condition with a 25% derate. It checks for a related code, reads harness voltage, and measures wire resistance to the ACM2.1.
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 4334 / FMI 3 |
| Fault name | DEF pressure sensor circuit failed high |
| Emissions platform | GHG14 |
| Pages | 2 |
| File size | 0.3 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com (© 2017); Detroit Power Service Literature |
DEF pressure sensor fault sections covered
The two-page routine screens for a shared short first, then uses voltage and resistance checks to place the fault.
- Monitored parameter and 25% engine derate; MIL and CEL
- Check for SPN 4334 and 3510 FMI 3 present together
- Disconnect the sensor and turn the key on
- Read voltage at pin 8 (greater than 0.5v flags a short)
- Measure resistance to ACM2.1 pin 99 (greater than 5 ohms)
- Repair the wire, or replace the DEF Dosing Unit
Applicable truck models
These steps cover Detroit DD-Series (DD13, DD15 and DD16) and Series 60 DDEC VI engines on the GHG14 platform with the ACM2.1 aftertreatment control module. Doser removal follows the “GHG14 Dosing System Doser” chapter in Detroit Power Service Literature at the Detroit Diesel official website.
Who needs this pressure sensor fault manual
This pressure sensor fault manual guides a workshop through SPN 4334 / FMI 3, using the voltage and resistance thresholds to decide between a harness repair and a dosing-unit replacement.
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 4334 / 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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