SPN 3242 FMI 4 is the Detroit DD Series fault-code procedure for a diesel oxidation catalyst inlet temperature sensor failed-low fault. This 2-page diagnostic PDF documents the fault, its monitored circuit on the diesel oxidation catalyst (DOC) inlet temperature sensor, and the exact troubleshooting steps a technician follows to confirm and repair the failure.
Official document details
| Brand | Detroit |
| Model coverage | DD Series (EPA 2007-Current); Series 60 DDEC VI |
| System / Group | DD Series / DTCs |
| SPN (fault code) | 3242 |
| FMI (failure mode) | 4 |
| Emission family | EPA10 / GHG14 calibration |
| Source | Detroit Power Service Literature (Copyright © 2017) |
| Pages | 2 |
| File size | 0.22 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN 3242, failure mode 4)
- Troubleshooting steps
- Sensor and ACM connector inspection
- Aftertreatment harness and resistance checks
Applicable truck models
This procedure applies to Detroit DD13, DD15 and DD16 engines in the DD Series (EPA 2007-Current) range and the equivalent Series 60 (DDEC VI) platform, as fitted to Freightliner and Western Star trucks. Confirm the EPA10 / GHG14 emission family matches the truck before following the steps; full model and coverage data is published on the Detroit official website.
Who needs this SPN 3242 FMI 4 manual
Diesel technicians, fleet workshops and mobile mechanics diagnosing a DOC inlet temperature sensor reading failed low on EPA10 or GHG14 Detroit engines need this reference to test the circuit correctly with a diesel diagnostic tool instead of replacing parts by guesswork.
SPN 3242 FMI 4 repair steps explained
The technician turns the ignition off, disconnects the DOC inlet temperature sensor and the Aftertreatment Control Module (ACM) 120-pin connector, and inspects both for bent, pushed-out, spread or corroded pins. Resistance from pin 2 on the harness side to battery ground below 1K ohm indicates a short to ground in the wire to pin 107 of the ACM. The 14-way or 47-way aftertreatment connectors and intermediate chassis wiring are also checked, and the sensor is replaced per the EPA10 or GHG14 Power Service Literature only after the wiring is verified with a diesel diagnostic tool.
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