DOC inlet pressure sensor — Detroit fault code SPN 3251 FMI 2

The DOC inlet pressure sensor fault sheet is the official Detroit DD Series diagnostic for an implausible DOC inlet-pressure signal, stored under SPN 3251 FMI 2 for EPA10, 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 2
Fault condition Diesel Oxidation Catalyst (DOC) Inlet Pressure – Not Plausible
Monitored parameter DOC inlet pressure
Emissions calibration EPA10, GHG14
Source / Publisher TruckFaultCodes.com
Year / Revision 2017
Pages 3
File size 0.3 MB
Format PDF
Language English

Document table of contents

  • Fault code identification: SPN 3251, FMI 2
  • Description and monitored parameter
  • Typical enabling conditions
  • Troubleshooting steps
  • Component inspection and repair verification

DOC inlet pressure sensor troubleshooting steps

The sheet has the technician confirm the code, inspect the sensor port, hose and harness for blockage or damage, and compare the reading against the diesel diagnostic tool before replacing the sensor or repairing the wiring.

Applicable truck models

This code sheet applies to trucks powered by Detroit DD Series diesel engines built to the EPA10, GHG14 emissions calibration; always match the SPN 3251 FMI 2 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 DOC inlet pressure sensor manual

Fleet technicians and independent workshops that service Detroit DD Series engines use this inlet pressure sensor 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.

The full PDF is available in the DiagTechPro manuals library; a free account is required to download it.

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