Which device reads diagnostic trouble codes from the vehicle's computer?

Which device reads diagnostic trouble codes from the vehicle's computer?

• A. A multimeter
• B. A scan tool
• C. A fuel gauge
• D. An oscilloscope

Answer: (B)

Reading diagnostic trouble codes involves connecting to the vehicle’s onboard computer and retrieving the stored fault codes, which is exactly what a scan tool does. The scan tool plugs into the OBD port and communicates with the engine control unit using the vehicle’s standard protocols, pulling out the DTCs and often showing a description, freeze-frame data, and live sensor readings. This is the tool designed specifically for accessing ECU fault information. A multimeter measures electrical values like voltage or resistance in circuits, which helps diagnose wiring or component issues but doesn’t read the ECU’s stored fault codes. An oscilloscope captures electrical waveforms to analyze signals over time, useful for detailed signal diagnosis but not for retrieving DTCs. A fuel gauge simply displays fuel level and has no role in diagnostic code retrieval. So, the device that reads diagnostic trouble codes from the vehicle’s computer is the scan tool.

Reading diagnostic trouble codes involves connecting to the vehicle’s onboard computer and retrieving the stored fault codes, which is exactly what a scan tool does. The scan tool plugs into the OBD port and communicates with the engine control unit using the vehicle’s standard protocols, pulling out the DTCs and often showing a description, freeze-frame data, and live sensor readings. This is the tool designed specifically for accessing ECU fault information.

A multimeter measures electrical values like voltage or resistance in circuits, which helps diagnose wiring or component issues but doesn’t read the ECU’s stored fault codes. An oscilloscope captures electrical waveforms to analyze signals over time, useful for detailed signal diagnosis but not for retrieving DTCs. A fuel gauge simply displays fuel level and has no role in diagnostic code retrieval.

So, the device that reads diagnostic trouble codes from the vehicle’s computer is the scan tool.