This code 249 DTCs document is a troubleshooting procedure for the ambient air temperature sensor 1 circuit on ISB6.7 CM2150 engines. It explains the code reason, diagnostic conditions, connector checks, resistance tests, ECM response checks, harness continuity checks, and fault-code clearing steps. The file is a 14-page English PDF intended for service diagnosis using INSITE™ and standard multimeter testing.
Official code 249 DTCs document details
| Brand | Cummins |
|---|---|
| Model coverage | ISB6.7 CM2150 (2007-09); extract also references ISB, ISC, and ISL ambient air temperature sensor 1 circuit coverage |
| System/Group | DTCs; Ambient Air Temperature Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source |
| Publication no. | Not shown in the extract |
| Year/Revision | Last Modified: 20-Jul-2010 |
| Pages | 14 |
| File size | 0.4 MB |
| Format | |
| Language | English |
Document table of contents
- Overview
- Circuit Description
- FAULT CODE 249
- Component Location
- Conditions for Running the Diagnostics
- Conditions for Setting the Fault Codes
- Action Taken When the Fault Code is Active
- Conditions for Clearing the Fault Code
- Shop Talk
- Associated Procedures
- Troubleshooting Steps
- Guided Step 1 – Check the fault codes.
- Guided Step 2 – Check the ambient air temperature sensor and circuit.
- Guided Step 3 – Check the ECM and engine harness.
- Guided Step 4 – Clear the fault codes.
Applicable truck models
This document applies to Cummins ISB6.7 CM2150 (2007-09) diagnostic work for Fault Code 249, PID P171, SPN 171, FMI 3/3. The extract identifies the ambient air temperature sensor 1 circuit and notes ISB, ISC, and ISL ambient air temperature sensor circuit references, but it does not list specific truck makes or chassis models. The procedure states that the sensor is located in the air intake and refers technicians to Procedure 100-002 for detailed component location. It also refers to QuickServe® Online calibration revision history and to Section 19 procedures for ECM calibration, connector inspection, resistance measurements, engine wiring harness repair, ambient air temperature sensor service, inactive or intermittent fault codes, and ECM replacement authorization. Manufacturer information is available from Cummins official website.
Who needs this code 249 DTCs manual
Workshop owners, diesel mechanics, and fleet technicians need this code 249 DTCs manual when an amber CHECK ENGINE light is active and the ECM reports high signal voltage on the ambient air temperature circuit. The procedure supports practical checks for dirty or damaged pins, sensor resistance from 1.6k ohms to 3.1k ohms, open return or signal circuits, pin-to-pin shorts greater than 100k ohms, and ECM response using INSITE™ electronic service tool.
The full PDF is available in the DiagTechPro manuals library, free account required to download.
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