SPN 84 FMI [2,9,10,19] How to Troubleshoot

SPN 84 is a diagnostic trouble code for wheel based vehicle speed data erratic.

FMI 2 – Intermittent Or Incorrect

FMI 9 – Abnormal Update Rate

FMI  10 -Abnormal Rate Of Change

FMI 19 –  Received Network Data In Error

Verify (ECM) electronic control module calibration
Clean (VSS) vehicle speed sensor connections


Cleaning the Vehicle Speed Sensor (VSS):

  1. Locate the VSS: Typically located on the transmission or transaxle.
  2. Remove the VSS: Disconnect the electrical connector from the VSS. Remove the VSS retaining bolt or clip, and carefully pull the it out of the transmission or transaxle.
  3. Clean the VSS: Use a soft brush or cloth to remove any dirt, debris, or metal shavings from the VSS. Be careful not to damage the sensor or the electrical terminals.
  4. Inspect the VSS: Check the VSS for any signs of damage, corrosion, or wear. If the sensor is damaged or worn, replace it with a new one.
  5. Reinstall the VSS: Carefully reinstall the VSS into the transmission or transaxle, and secure it with the retaining bolt or clip. Reconnect the electrical connector.
  6. Reconnect the battery: Reconnect the negative battery terminal, and start the engine to ensure proper operation. Test drive around the block.



Wheel-based vehicle speed data is the information collected by a vehicle’s wheel speed sensors, which measure the rotational speed of the wheels. This data is essential for several vehicle systems, including the anti-lock braking system (ABS), electronic stability control (ESC), and traction control system (TCS). It can also be used by the engine control unit (ECU) or engine control module (ECM) to optimize engine performance, transmission shifting, and cruise control operation.

Wheel speed sensors are typically located near the wheel hubs or inside the wheel bearings. They can be either active or passive sensors. Active sensors use a combination of a magnet and a coil to produce a digital signal, while passive sensors generate an analog signal using a magnetic pickup and a toothed ring on the wheel hub.

Other SPN codes: