HEM Data Products

DAWN OBD Inspector™ (CARB-approved version)

A version of the DAWN OBD Inspector™ has been approved by the California Air Resource Board (CARB) for their Clean Truck Check and is described on this webpage.

For other inspection applications of the DAWN OBD Inspector including detecting tampering click here.

DAWN OBD Inspector™ is a small, easily portable solution and quick to install. It is ideal for the roaming inspector or at a service site. Just attach the hardware to the vehicle network connector, turn on the engine, and open the smart phone app. Complete the test within 2 minutes. DAWN (Data Acquisition With Network) is the umbrella name for HEM Data’s products.

California Clean Truck Check

The California Air Resources Board (CARB) has developed the Clean Truck Check to ensure that heavy-duty vehicle emission control systems function properly and that emissions remain low throughout their operating life. The Clean Truck Check applies to nearly all diesel and alternative fuel vehicles with a gross vehicle weight rating (GVWR) of over 14,000 pounds, including all out-of-state and out-of-country vehicles. Vehicles with diesel engines that are model year 2013 and newer (and 2018 and newer hybrid or alternative fuel engines) are required to submit OBD data. Data is acquired using the vehicle’s OBD system to determine whether a vehicle’s emission control systems are functioning properly.

Interested test personnel must successfully complete a free online training session from CARB. An approved tester will receive a Tester ID that is valid for 2 years. A Test ID is required to use OBD Inspector. See the details of the CARB Clean Truck Check.

Components of DAWN OBD Inspector™

The DAWN OBD Inspector consists of three components

  • CAN Mini Streamer™ hardware (dongle)
  • iPad or iPhone (iOS 12.4 and up)
  • DAWN OBD Inspector™ software

CAN Mini Streamer™ Hardware

HEM Data’s CAN Mini Streamer sends the vehicle data to the OBD Inspector app. The Mini Streamer hardware conveniently fits directly on the 9-pin J1939 connector. An adapter cable works for the 16-pin OBD-II connector. Baud rates of 250k, 500k, and 1000k are automatically detected.

CAN Mini Streamer™

The Mini Streamer acquires all necessary vehicle data and sends it wirelessly to the DAWN OBD Inspector™ app. Therefore, test personnel don’t need to climb into the cab.

OBD Inspector™ Software

OBD Inspector is supported on both an iPad and iPhone. As the app receives the data from the Mini Streamer hardware using a WiFi connection, the app displays real-time information to the user as the test is progressing. CARB requires that the app have internet access to start the test so that the data is immediately forwarded to the CARB website.

The app is approved by CARB for J1979 and J1939 support. Contact sales@hemdata.com for the latest update. The app is on the Apple App Store. To activate the app, a license needs to be purchased from HEM Data.

Below is a screenshot of the real-time data during the test. The progress bar at the bottom shows the user when the test has been completed.

Parameters table showing live data

The screenshot above shows the live values table. A progress bar is shown at the bottom.

Pricing Information

The DAWN OBD Inspector pricing is as follows:

  • The Mini Streamer hardware purchase is $395 (one-time fee)
  • The software license is $995 (one-time fee including first year)
  • The yearly renewal is $500

Adapter Option

  • Adapter Y cable to both the 9-pin J1939 and the 16-pin J1962 (OBD-II) (used on Volvo and Mack trucks and many medium-duty trucks). Price is $39.

VIN Reader

CARB requires that the VIN be entered manually which is easy to mistype. A barcode reader app on youriOS device is a quick way to copy the VIN into the OBD Inspector app.


To purchase or receive answers to your question, send an email to sales@hemdata.com. Or call our office at 248 559-5607 x111.

The DAWN OBD Inspector is also adaptable to a variety of inspection applications. Click here for details.

J1939 Mini Logger™ OBD Mini Logger™ DAWN Telematics™ DAWN™ Software ADAQ Mini™ DAWN Dashboard™