# Service bulletin D21M6REV4

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service bulletin
- NHTSA id: 10233947
- Published by NHTSA: 2023\-04\-07
- Manufacturer's number: D21M6REV4
- Manufacturer's date: 2023\-03\-31
- NHTSA component: ENGINE AND ENGINE COOLING

## NHTSA's summary

Revised Detroit Field Service Campaign for Gen 5 Customer Demo Unit \(CDU\) and Pre\-Series Unit Retrofits. D21M6 REVISION : Page 1 of the bulletin under "Replacement Parts" and "IMPORTANT" have been revised.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2023/MC-10233947-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2023/MC-10233947-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Engine

## Vehicles listed

- 2021 FREIGHTLINER CASCADIA

## Recalls for the same vehicles and component

- [21V073000](/recalls/nhtsa/21V073000.md), 2021-02-12: ENGINE

## Other bulletins for the same vehicles and component

- [FleetCom\_Heater Core](/bulletins/11027493.md), 2026-01-08, Other: ENGINE. Fleet Communications for Heater Core Plugging
- [FleetCom\_SS 3163\-FTL](/bulletins/11026453.md), 2025-12-06, Other: ENGINE. Fleet Communications for Power Steering Reservoir Fill Cap Venting
- [FleetCom\_Low Coolant](/bulletins/11026421.md), 2025-12-05, Other: ENGINE. Fleet Communications for Low Coolant Sensor
- [CXA\_10\_25\_Low Coolant](/bulletins/11024962.md), 2025-11-05, Other: ENGINE. CX Advocate for P4, WST X\-Series, DD Engines Low/Critical Low Coolant Warnings
- [CXA\_10\_25\_Conmet Oil Pan](/bulletins/11024958.md), 2025-11-05, Other: ENGINE. CX Advocate for ConMet Oil Pan Insert Additional Issues
- [CXA\_9\_25\_Tech Questions](/bulletins/11023683.md), 2025-10-03, Other: POWER TRAIN; ENGINE. CX Advocate for technical questions/issues raised
- [CXA\_8\_25\_Tech Questions](/bulletins/11022341.md), 2025-09-02, Other: POWER TRAIN; ENGINE; UNKNOWN OR OTHER. CX Advocate for technical questions/issues raised
- [CXA 3\_25\_NOx](/bulletins/11016309.md), 2025-04-02, Other: ENGINE. CX Advocate for NOx conversion low faults
- [CXA 2\_25\_Turbo Oil Drain](/bulletins/11014819.md), 2025-03-04, Other: ENGINE. CX Advocate for turbo oil drain cracking
- [CXA 2\_25\_NOx](/bulletins/11014818.md), 2025-03-04, Other: ENGINE. CX Advocate for NOx conversion low faults

JSON: [/v1/bulletins/10233947](/v1/bulletins/10233947)

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