# Service bulletin TSB230168

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: 11036019
- Published by NHTSA: 2026\-08\-07
- Manufacturer's number: TSB230168
- Manufacturer's date: 2026\-07\-07
- NHTSA component: ENGINE

## NHTSA's summary

This Technical Service Bulletin describes the verification and resolution steps for the engine control module calibration of certain B6.7 engines in Hybrid Transit and School Bus applications which may falsely detect an issue with the engine cooling system when ambient conditions are below 4 °C and auxiliary heating systems affect coolant temperatures , resulting in fault code 3243 being set. This is an update to a previously submitted communication.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2026/MC-11036019-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2026/MC-11036019-9999.pdf)

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

## Components

Engine

## Vehicles listed

- CUMMINS B6.7

JSON: [/v1/bulletins/11036019](/v1/bulletins/11036019)

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