SPN 3242 FMI 3 is the Detroit DD Series fault-code procedure for a diesel oxidation catalyst inlet temperature sensor circuit failed-high fault. This 3-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) | 3 |
| Emission family | EPA10 / GHG14 calibration |
| Source | Detroit Power Service Literature (Copyright © 2017) |
| Pages | 3 |
| File size | 0.31 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN 3242, failure mode 3)
- Troubleshooting steps
- DOC inlet temperature sensor resistance and voltage checks
- Removal reference in Power Service Literature
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 3 manual
Diesel technicians, fleet workshops and mobile mechanics diagnosing a DOC inlet temperature sensor reading failed high 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 3 repair steps explained
The procedure has the technician disconnect the DOC inlet temperature sensor, inspect the harness for bent, spread or corroded pins, then measure resistance between pins 1 and 2. With the ignition on, voltage at pin 2 should read between 2.75 and 3 volts; readings outside that range point to a short to power, an open, or a damaged wire between the sensor and pin 107 or pin 108 of the Aftertreatment Control Module (ACM) 120-pin connector. If the sensor is out of range it is replaced per Detroit Power Service Literature.
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