Gerrit van Rensburg
Founder, Tachwise
Gerrit van Rensburg is the founder of Tachwise. He has an electrical engineering background and a lifelong passion for cars: he grew up in a small town with a racetrack, where he got his first job. In Canada, he built and bench-tests the Tachwise OBD-II device prototype (a Raspberry Pi Pico 2 W with a CAN transceiver), captured OBD-II port traffic on a production car, built the Tachwise app beta that reads trouble codes through ELM327 adapters, and wrote a physics-based OBD-II simulator for testing.
Areas of expertise
- Electrical engineering
- Automotive electronics
- OBD-II diagnostics
- Car batteries
Elsewhere
Articles
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Do Uber, DoorDash and Skip drivers have to charge GST/HST?
Rideshare drivers in Canada register for GST/HST from their first fare; delivery-only drivers register at $30,000 over four quarters. What the CRA says.
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How do taxes work for Uber, DoorDash and Skip drivers in Canada?
Gig drivers in Canada are self-employed: report all income and tips, deduct the business share of car costs, pay both halves of CPP. The CRA's rules.
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How much wear does DoorDash or Uber put on your car?
Carmakers class taxi and delivery driving as severe service, with shorter intervals for oil, fluids and brakes. What changes, and how to put a cost on wear.
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Is DoorDash or Uber worth it after gas? How to work out your real pay
Your real pay is payouts minus fuel and wear, divided by every hour you're signed in, waiting included. The formula, fuel cost per km, and a worked example.
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What should an Uber or DoorDash mileage log include?
The CRA and the IRS ask for the same four things per work trip: date, distance, destination and purpose, kept at the time. How to log rideshare driving.
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Are Bluetooth car battery monitors any good?
A Bluetooth car battery monitor is a logging voltmeter: good for catching drains, low charge and charging faults, but it can't measure battery health.
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Can you leave an OBD2 scanner plugged in all the time?
Yes while driving; parked, it depends on the adapter's sleep current. Published draws, how fast they drain a car battery, and when to unplug an OBD2 dongle.
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Can you use an OBD2 scanner without a subscription?
You don't need a subscription to read check-engine codes: the emissions data is standard by law. What scanner subscriptions add, and how to choose without one.
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Does OBD2 work on all cars?
OBD2 works on US cars and light trucks from 1996 (diesels 1997) and on Canadian ones by 2004. The exceptions: older cars, heavy trucks, imports and many EVs.
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Why does my car battery keep dying?
Car battery keeps dying? It's usually worn out, undercharged by short trips, let down by the alternator, or drained while the car is off. How to tell which.
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Why won't my ELM327 adapter work with my iPhone?
Most cheap ELM327 adapters use classic Bluetooth, which iPhone apps can't reach unless the maker joined Apple's MFi program. Which ones work, and how to tell.
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Why won't my OBD2 scanner connect to the car?
OBD2 scanner not connecting to the car or ECU? Usually the ignition is off, the port's fuse is blown, the Bluetooth type is wrong or the protocol fails.
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Car won't start and just clicks: battery, starter, or something else?
A click but no crank usually points to a flat battery or a bad connection, sometimes the starter. How to tell which, jump-start safely, and when to stop trying.
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Check engine light on: can I keep driving?
Steady check engine light: usually drivable, get the code read soon. Flashing: a severe misfire, so slow down and stop when safe. When to pull over right away.
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How long can a car sit before the battery dies?
How long a parked car's battery lasts depends on its parked draw, size, age and temperature. The math, what carmakers advise, and how to store a car safely.
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How long do you need to drive to recharge a car battery?
There's no reliable drive time to recharge a car battery. What battery makers say, what decides it (loads, rpm, cold, age), and why a charger works better.
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How much does idling cost a fleet?
A light-duty engine burns roughly 1 to 1.8 litres of fuel an hour at idle. How to work out what that costs your fleet each year, and how to cut it.
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How much EV battery degradation is normal?
Every EV battery loses some capacity. What the Hyundai, Nissan and Tesla warranties treat as abnormal, what speeds wear up, and how to check your own battery.
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Pending, stored and permanent trouble codes: what's the difference?
Pending codes (mode 07) are early warnings, stored codes (mode 03) turn the light on, and permanent codes (mode 0A) can't be erased by a scan tool. Here's why.
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U0100 (lost communication with the engine computer): what it means
U0100 means other modules stopped hearing from the engine computer. The causes carmakers' bulletins name, why it can mean stalling, and what to check first.
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What is a normal car battery voltage?
Car battery voltage chart for flooded and AGM 12 V batteries: resting, charging and cranking voltages, how to measure them, and what each reading means.
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What is a normal parasitic battery drain, and how do you find one?
Normal parasitic drain is tens of milliamps once a car's modules sleep. How long to wait, how to measure it safely, and how to trace a drain to its circuit.
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What vehicle health data can OBD-II give a fleet manager?
OBD-II gives codes, check engine light status, readiness, live engine data, VIN and port voltage. It can't see tire tread, most brake wear or J1939 trucks.
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Why do car batteries die in cold weather?
Cold slows a car battery's chemistry as thick oil makes the engine harder to crank. What that means at −20 °C, when a battery can freeze, and how to prepare.
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Why does my car say "not ready" for an emissions test?
Not ready means your car's OBD self-tests haven't finished since codes were cleared or the battery was disconnected. How many are allowed, and how to set them.
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Is gas really cheaper on Tuesday? Where it is, and where it isn't
Cheapest-weekday tips travel badly. Toronto had weekly price cycles, Australian cities run one- to six-week cycles and Vancouver follows wholesale supply.
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Does DC fast charging hurt an EV battery?
DC fast charging can add some battery wear, mostly through heat. What Idaho National Laboratory measured, what carmakers advise, and how to fast charge gently.
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How should a small fleet schedule preventive maintenance?
Schedule each vehicle from its maker's maintenance schedule, by distance, time and engine hours, whichever comes first, and keep one record per vehicle.
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P0171 (system too lean) and fuel trims explained
P0171 means bank 1 is running lean and the engine computer has run out of fuel trim to fix it. What fuel trims are, normal ranges, and the common causes.
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What should a pre-trip inspection cover for light-duty fleet vehicles?
Daily inspection rules cover interstate commercial vehicles from 10,001 lb (US) and trucks over 4,500 kg (Canada). Below that, a walk-around is good practice.
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When should a fleet replace vehicle batteries?
Test every fleet battery at least yearly before winter, watch batteries three to five years old closely, and replace on a failed test, not a no-start.
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When should you plug in a block heater, and for how long?
Plug in at about −15 °C (5 °F) or colder, two to four hours before you leave. What NRCan, CAA-Quebec and a maker's manual say, plus safe cord habits.
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Why do EV 12-volt batteries die, and how do you avoid it?
An EV's small 12-volt battery can leave the car dead even with a charged main pack. Why it goes flat, the warning signs, and what owner's manuals say to do.
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P0101 (mass airflow sensor range/performance) explained
P0101 means the airflow sensor's reading doesn't agree with the engine's other sensors. What sets it, causes in carmakers' bulletins, and whether to drive.
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P0128 (coolant below thermostat temperature): causes and why it matters in winter
P0128 means your engine didn't warm up to its thermostat temperature in time. What sets it, the usual causes, and why a cold-running engine matters in winter.
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P0300 (random or multiple misfire): what it means and whether you can drive
P0300 means misfire in more than one cylinder, or in one the computer can't identify. What sets it, the common causes, and when a flashing light means stop.
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P0420: what it means, common causes, and whether you can drive
P0420 means your bank 1 catalytic converter tested below its efficiency threshold. What the car measures, the common causes, and when it is safe to drive.
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P0455 and P0442 (EVAP leak): is it just the gas cap?
P0455 and P0442 mean the EVAP system found a large or a small fuel-vapor leak. How the car tests for it, when it is the gas cap, and what else to check.
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Hear first when the Tachwise device is ready
Join the free waitlist: no payment, no deposit. Or try the app beta today; it reads your car's codes through your own ELM327 Bluetooth dongle.