The Detroit DOC inlet pressure fault sheet is the official Detroit DD Series diagnostic for an implausible DOC inlet-pressure signal, stored under SPN 3251 FMI 20 for GHG14 calibrations. It records the monitored parameter DOC inlet pressure, exactly as published by TruckFaultCodes.com (© 2017).
Official document details
| Brand | Detroit |
|---|---|
| Model coverage | Detroit DD Series diesel engines (EPA 2007-current) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 3251 / FMI 20 |
| Fault condition | Diesel Oxidation Catalyst (DOC) Inlet Pressure – Not Plausible |
| Monitored parameter | DOC inlet pressure |
| Emissions calibration | GHG14 |
| Source / Publisher | TruckFaultCodes.com |
| Year / Revision | 2017 |
| Pages | 3 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification: SPN 3251, FMI 20
- Description and monitored parameter
- Typical enabling conditions
- Troubleshooting steps
- Component inspection and repair verification
Detroit DOC inlet pressure troubleshooting steps
The sheet has the technician confirm the code, inspect the DOC inlet pressure sensor, its port and harness, and compare the reading against the diesel diagnostic tool before deciding whether the sensor, hose or wiring is at fault.
Applicable truck models
This code sheet applies to trucks powered by Detroit DD Series diesel engines built to the GHG14 emissions calibration; always match the SPN 3251 FMI 20 listing to the vehicle’s own engine family before repair. Confirm the emissions family on the vehicle emissions label, because aftertreatment and dosing hardware differs between the EPA07, EPA10 and GHG14 builds and a mismatched procedure can send you to the wrong component. For engine coverage and dealer service information, see the Detroit Diesel official website.
Who needs this Detroit DOC inlet pressure manual
Fleet technicians and independent workshops that service Detroit DD Series engines use this DOC inlet pressure reference to confirm the code, its enabling conditions and the correct repair before replacing parts. It is written for the mechanic making the repair decision, not the driver, and pairs with the wiring diagrams and component removal procedures Detroit publishes in Power Service Literature.
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