Mass Air Flow Sensor

This procedure covers the replacement of the Mass Air Flow (MAF) sensor on a 2007 Ram 3500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Mass Air Flow sensor × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn ignition to OFF position and remove key
3. Allow engine to cool if recently operated
4. Open hood and secure with prop rod

Procedure

1. 1

   Locate the sensor
   The intake air temperature sensor (IAT) is mounted in the intake manifold air horn/grid heater area on the 5.9L Cummins. Verify the exact location against the factory service manual before proceeding, as this platform does not use a traditional MAF sensor. If an aftermarket MAF sensor is installed, it will be in the intake tubing between the air filter and turbocharger inlet.
2. 2

   Disconnect electrical connector
   Press down on the tab on the electrical connector and pull the connector straight off the sensor. Do not pull on the wiring harness itself.
3. 3

   Remove sensor mounting screws
   Confirm the sensor retention method against the factory service manual. Depending on the sensor type it may be a threaded screw-in unit (removed with a wrench/socket) or a flange sensor secured by mounting screws; use the correct tool for the actual fastener present. Keep these screws in a safe location for reinstallation.
4. 4

   Extract the sensor
   Carefully pull the sensor straight out of the intake manifold or tubing. There may be an O-ring seal that comes out with the sensor. Inspect the O-ring for damage or deterioration.
5. 5

   Clean the mounting location
   Use a clean microfiber cloth to wipe away any dirt or debris from the sensor mounting bore in the intake manifold or tubing. Ensure no debris falls into the intake system.
6. 6

   Install new sensor
   If the new sensor includes a new O-ring, install it onto the sensor body. Insert the new sensor into the mounting bore, ensuring proper alignment and that the O-ring seats correctly. Do not force the sensor.
7. 7

   Secure sensor with mounting screws
   Reinstall the sensor using the retention method appropriate to the actual fastener type, and torque to the factory specification listed in the service manual. Do not over-tighten, as this can crack the sensor body or damage the threads.
8. 8

   Reconnect electrical connector
   Push the electrical connector onto the sensor until you hear and feel a positive click, indicating the locking tab has engaged. Gently tug on the connector to verify it is secure.

Reassembly

1. Close hood securely
2. No additional reassembly required for this procedure

Verification

• Start the engine and verify it idles smoothly without any rough running or hesitation
• Check for any diagnostic trouble codes using a scan tool - there should be no MAF or IAT sensor codes present
• Verify the intake air temperature reading on a scan tool matches ambient temperature when engine is cold
• Road test the vehicle to ensure normal acceleration and throttle response
• Recheck electrical connector after test drive to ensure it remains secure

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