This Detroit DEF pressure sensor sheet documents fault code SPN 4334 / FMI 4 on GHG14 engines, a circuit-failed-low condition with a 25% derate. The three-page procedure checks for related codes, reads dosing-unit voltages, 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 4 |
| Fault name | DEF pressure sensor circuit failed low |
| Emissions platform | GHG14 |
| Pages | 3 |
| File size | 0.3 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com (© 2017); Detroit Power Service Literature |
Detroit DEF pressure sensor sections covered
The routine screens for a shared code first, then works through supply voltage and a resistance check on the dosing harness.
- Monitored parameter and 25% engine derate; MIL and CEL
- Check for SPN 4334 and 3510 FMI 4 present together
- Inspect the dosing unit connector for damage or unseated pins
- Read supply voltage (4.5 to 5.5 volts) at the dosing harness
- Measure resistance to ACM2.1 pin 100 (greater than 5 ohms)
- Repair the wire, or replace the DEF Doser 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 Detroit DEF pressure sensor manual
This DEF pressure sensor manual guides a workshop through SPN 4334 / FMI 4, using voltage and resistance checks to decide between a harness repair and a full doser-unit replacement.
The full 3-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 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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