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Intermittent is when a problem or error comes and goes with no obvious observations, warnings, or trouble codes. In order to help in finding intermittents, a scan tool can be used as equipment when performing a road test or troubleshooting or diagnostic procedures. Some scanners can take a snapshot or act as a recorder and can store scanned data during a road test, This is played back and analyzed after the vehicle returns to the shop.

  • Some automotive manufacturers require the use of a scan tool or readout box. to perform system diagnosis, especially for intermittent problems.
  • It is connected to the diagnostic connector and can be read b y the technical while performing roadtest or working in the engine compartment. 
  • The scan tool provides information more quickly than the instrument panel light; It is also capable of displaying numbers and words which are less likely to be misread than the series of flashes provided by the light
  • This scan tool is capable of providing information that would be very difficult or impossible to obtain. It can retrieve trouble code and displays the PROM ([Programmable Read-Only Memory) identification number, which displays the ECM (electronic control module) data values and parameters that indicates the problem even if no trouble code is set. It gives the status or condition of many input and output devices