FOXWELL NT604Pro OBD2 Scanner and 12V Battery Tester

The NT604Pro is FOXWELL's update to the NT604 four-system scanner, and the reason to pick it over the older unit is the built-in 12V battery tester. It still reads and clears codes on the engine, transmission, ABS and SRS airbag modules and streams live data from all four, but it now also runs a battery, cranking and charging test through a set of clamps, so a no-start or hard-start car can be sorted out with one tool instead of two.

On the transmission side it does the job that matters most on a modern sealed unit: it pulls transmission fluid temperature as a live PID. Most late-model automatics have no dipstick and have to be filled with the fluid inside a narrow temperature window, usually somewhere around 100 to 120 degrees F depending on the manufacturer's procedure. Fill it hot or cold and the level reads wrong, which is how a unit ends up low and burning a 3-4 clutch pack a few thousand miles later. Watch the temp climb on the NT604Pro, crack the fill plug at the right number, and the level is right the first time. It also reads transmission DTCs and live data such as turbine and output shaft speed on supported vehicles, which is how you tell a slipping clutch pack from a bad speed sensor before anything comes apart.

The battery side runs in three steps. The battery test reports state of health, CCA, state of charge and internal resistance. The cranking test records cranking voltage and cranking time so you can see whether the starter is dragging the system down. The charging test reads alternator output voltage and checks for ripple, which catches a diode failing in the rectifier before the battery gets cooked. That sequence tells you whether you are replacing a battery, a starter or an alternator instead of throwing a battery at it and hoping.

It adds three service resets that the plain NT604 does not have: oil service reset after an oil change, BMS registration after a 12V battery replacement, and throttle position relearn after cleaning or replacing a throttle body. Everything runs off the 4.3-inch color screen with real buttons, no phone or app required, and software updates are free over WiFi. Coverage for the four-system diagnostics and the service resets varies by year, make and model, so check your specific vehicle before counting on a given function. In the box: the NT604Pro, the OBDII diagnostic cable, the battery clamp cable, a USB-C cable and a nylon carry pouch.