Stahlcar ST350 OBD2 Tool for Leaf Spy + Dr Prius Apps

The ST350 is the communication hardware. It plugs into the vehicle’s diagnostic socket and sends data wirelessly to the selected app. The phone or tablet provides the screen, menus, tests, reports and available service functions.

That distinction matters. The ST350 does not contain Leaf Spy or Dr Prius software and does not unlock paid app features by itself. Its job is to provide the stable vehicle connection those apps require.

Best Suited For

The ST350 suits Nissan Leaf and e-NV200 owners who want detailed EV battery information, Toyota and Lexus hybrid owners who want to monitor or test the high-voltage battery, and households or workshops that work with both vehicle groups.

It is especially useful for pre-purchase inspections, monitoring battery condition over time, investigating cell or block imbalance, checking battery temperature and recording information before deciding whether further workshop diagnosis is needed.

Using the ST350 with Leaf Spy

Leaf Spy can retrieve detailed Nissan EV information that is not normally shown on the dashboard. This is useful because the dashboard battery bars and estimated range provide only a simplified view of battery condition.

The app can be used for routine ownership, comparing used vehicles, investigating charging behaviour and recording battery information over time.

Leaf Cell-Pair Voltage and Balance

Leaf Spy can display the voltage of each traction-battery cell pair, together with the minimum, average and maximum values. Graph and histogram views make it easier to see whether one section of the battery is separating from the rest.

A small difference between the highest and lowest cell-pair voltage is normal. The difference can increase when the battery is at a low state of charge or supplying high power. A cell pair that repeatedly moves well away from the others may justify further investigation.

The app can also highlight cell pairs where the battery-management system is operating a balancing shunt.

Leaf Battery Temperatures and Charging Information

Leaf Spy can display readings from the traction-battery temperature sensors, including minimum, average and maximum temperature. This is particularly useful because earlier Leafs use an air-cooled battery rather than an actively liquid-cooled pack.

Battery temperature can rise during sustained high-speed use, hot weather and repeated rapid charging. Monitoring it can help the driver make a more informed decision about continuing a long journey or adding another rapid charge.

The app can also show rapid-charge and standard AC charge counts, EVSE maximum available current and EVSE voltage on supported vehicles and charging equipment.

Leaf Spy Pro Diagnostic and Setting Functions

Leaf Spy Pro adds functions that would otherwise normally require specialist equipment. Availability depends on the Leaf model year.

• Read Diagnostic Trouble Codes: Checks supported Leaf control units for stored faults.
• Reset Selected Codes: Clears supported codes after the cause has been repaired.
• Tyre Position Registration: Assigns TPMS sensors to the correct wheel positions after rotation or wheel changes where supported.
• Automatic Door-Lock Settings: Changes selected automatic lock and unlock behaviour.
• Pedestrian Sound Settings: Adjusts selected VSP settings on supported 2013–2017 Leafs.
• Dashboard Language: Changes the instrument display language on supported earlier Leafs.
• P3102 Reset: Clears the supported battery-replacement code after a different traction battery has been installed.

Using Leaf Spy for a Used-Vehicle Inspection

The traction battery is one of the most important and expensive parts of a used Nissan Leaf. Leaf Spy helps the buyer look beyond the dashboard capacity bars and advertised range.

Useful checks include recording the state-of-health and amp-hour values, comparing cell-pair voltages, checking battery temperature, reviewing charging counts, scanning for fault codes and saving screenshots so several vehicles can be compared later.

A Leaf Spy check should be combined with a normal road test, charging test, brake and tyre inspection, 12V battery check and confirmation that the available real-world range suits the buyer’s needs.

Using the ST350 with Dr Prius / Dr Hybrid

Dr Prius is designed to help owners and repairers examine the high-voltage traction battery fitted to supported Toyota and Lexus hybrids. It can display the individual battery blocks, compare their behaviour and guide the user through dedicated battery-health tests.

The app is useful when investigating hybrid battery warning lights, checking an ageing battery, assessing a vehicle before purchase or confirming which block appears weaker than the rest.

Identifying Weak Hybrid Battery Blocks

A healthy battery normally has blocks that charge and discharge in a reasonably similar way. A weak block may change voltage faster than the others or repeatedly show a larger difference during driving and testing.

Dr Prius uses colour-coded charts and numerical data to make these differences easier to see. Voltage and internal-resistance information can help identify which area of the pack deserves closer attention.

Dr Prius Life Expectancy Test

The Life Expectancy Test is a guided test that uses the app’s proprietary algorithm to estimate the remaining condition of the hybrid battery. The app instructs the user through a controlled charge and discharge process while monitoring the battery.

The test takes longer than simply viewing the monitor screen and should be carried out in a safe, ventilated area with the vehicle secured and the instructions followed carefully.

The result can be useful for comparing vehicles, tracking an ageing pack or providing a clearer indication of overall battery performance than one momentary voltage reading.

Dr Prius Full Battery Test and Test Certificate

The Full Battery Test provides a more detailed guided diagnostic process for the hybrid battery. It is intended to place the battery through controlled operating conditions while the app checks block behaviour.

Supported app packages can generate a battery test result or certificate that can be saved, printed or shared. This can be useful when documenting a pre-purchase inspection, showing a customer the test outcome or recording battery condition before and after repair.

Dr Prius Diagnostic and Special Functions

Depending on the exact vehicle and app version, Dr Prius may also provide:

• Read and Clear Trouble Codes: Checks supported hybrid systems and resets selected codes after repair.
• Battery Fan Control: Allows supported battery cooling-fan operation to be adjusted or overridden for testing and hot-weather use.
• Reverse-Beep Setting: Changes the supported reverse warning behaviour.
• Seat-Belt Beep Setting: Changes selected seat-belt reminder behaviour where supported.
• Maintenance Mode: Places supported Toyota hybrids into the special operating mode used during selected diagnostic or service procedures.
• Traction-Control Setting: Provides supported traction-control on or off functions for specific procedures and vehicles.

Dr Prius Vehicle Coverage

The app supports a broad range of Toyota and Lexus hybrid vehicles. Common supported models include:

• Toyota Prius generations 1 through 5, with partial support on some early models
• Prius Plug-In and Prius Prime
• Prius C and Toyota Aqua
• Prius V and related wagon models
• Toyota Auris Hybrid
• Corolla Axio and Fielder Hybrid
• Toyota Camry and Avalon Hybrid
• Toyota Highlander Hybrid
• Toyota C-HR Hybrid and Plug-In Hybrid
• Selected Estima, Sienna, Tundra and Tacoma hybrid models
• Lexus CT200h, ES300h, HS250h, GS450h and LS600h
• Lexus RX400h, RX450h and UX250h
• Other models added by the app developer

Coverage and test support are not identical across every model. The vehicle must appear on the current Dr Prius support list, and some early or less common models have partial coverage.

Third-Party App Costs

Phone, App and Connection Requirements

A compatible Android or iOS phone or tablet with Bluetooth Low Energy is required. Install the intended app before use and select the ST350 or compatible BLE adapter type inside the app settings.

Bluetooth Low Energy adapters often connect through the diagnostic app rather than appearing like a normal audio accessory in the phone’s Bluetooth menu.

Internet access is needed to download, update or purchase app features. Normal communication with the vehicle takes place directly between the app, ST350 and car.

Basic Setup

1. Install Leaf Spy, Dr Prius or the intended compatible app.
2. With the vehicle switched off, plug the ST350 into the standard OBD2 socket.
3. Turn the vehicle on or place it in the operating mode required by the app instructions.
4. Open the app and select the correct Bluetooth Low Energy adapter type.
5. Allow the app time to connect and populate the battery information.
6. Confirm that live values are updating before starting a guided test.
7. Follow the app instructions exactly for any battery life, full battery or service-mode procedure.

Remove the ST350 if the vehicle will be parked unused for a long period. Any adapter left in a permanently powered OBD socket can contribute to 12V battery drain over time.