Massey Ferguson 4201.02 – Engine Control Unit (ECU): Crankshaft Speed Sensor Signal Issue (ECU) / Crank speed signal erratic, too much noise pulses

The engine's crankshaft speed and angular position evaluation module expects a defined sequence of pulses from the crankshaft speed sensor. If the sensor detects too many pulses between two gaps (indicating an erratic signal or heavy electrical interference/noise), the system logs this fault.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724

1. 1

   Check the engine wire harness leading to the crankshaft speed sensor for rub points, melted insulation, or shorts to ground, and ensure the connector is securely seated and free of corrosion or moisture.

2. 2

   Check for signal interference sources such as poor engine grounds, failing alternator diodes, or unshielded wiring routed too close to the sensor harness.

3. 3

   Remove the sensor and inspect the magnetic tip, cleaning off any metallic debris or sludge that could distort the magnetic field.

4. 4

   Inspect the crankshaft tone wheel through the sensor mounting hole for damaged, bent, or missing teeth.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery terminal to prevent electrical shorts and reset the ECU.

2. 2

   Locate the Sensor

   Locate the crankshaft speed sensor on the engine block (typically near the crankshaft pulley or flywheel housing, depending on the specific AGCO Power engine layout).

3. 3

   Removal

   Disconnect the electrical harness connector from the sensor. Remove the retaining hex cap screw/bolt and carefully pull the sensor out of the block.

4. 4

   Installation

   Lubricate the O-ring on the new sensor with a small amount of clean engine oil. Insert the new sensor into the port until it seats fully.

5. 5

   Secure

   Install the retaining bolt and tighten to OEM specifications. Reconnect the electrical harness.

6. 6

   Clear Codes

   Reconnect the battery. Use a compatible diagnostic service tool (like WinEEM3s/EEM4) to clear the inactive 004201.02 fault code from the Engine ECU. Start the engine and verify that the code does not return.