SPN 520232 FMI 9 is the Detroit Diesel fault-code service sheet that documents a NOx mass signal that is not available over the CAN network. It is a short powertrain-CAN communication check that ties back to the wider network diagnosis. This DiagTechPro library page summarizes what the 1-page PDF contains so a technician can confirm it is the right document before downloading.
Official document details
| Brand | Detroit (Detroit Diesel) |
|---|---|
| Model coverage | DD Series (EPA 2007-Current); Series 60 DDEC VI (EPA 2007) |
| System / group | GHG14 diagnostic trouble codes |
| Suspect Parameter Number | 520232 |
| Failure Mode Identifier | 9 |
| Source | TruckFaultCodes.com, © 2017 |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault description: NOx mass signal over CAN
- Step 1: recent ACM2.1/MCM2.1/CPC4 reprogramming
- Steps 2-4: power-down and re-check sequence
- Escalation: SPN 625/FMI 9 powertrain-CAN
SPN 520232 FMI 9 diagnostic summary
The sheet first asks whether the ACM2.1, MCM2.1 or CPC4 has been recently reprogrammed; if so, clearing the codes and confirming they do not return is enough to release the vehicle. Otherwise the technician turns the ignition off, disconnects the diesel diagnostic tool, and waits five minutes for all modules to power down before cycling the ignition on and reconnecting. If the fault codes are still active, the document refers the technician to the complete SPN 625/FMI 9 procedure for further powertrain-CAN troubleshooting.
Applicable Detroit truck models
This fault-code sheet applies to Detroit DD Series engines certified to EPA 2007 and later emissions standards, and it is cross-listed under the Detroit Series 60 (DDEC VI, EPA 2007) diagnostic set. For full engine specifications and support details, see the official Detroit website.
Who needs this 520232 FMI 9 manual
Detroit technicians dealing with an emissions or torque limitation caused by missing network data use this sheet to rule out a reprogramming artifact before opening a full CAN investigation.
The complete PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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