If you've called us looking for a dash, a data logger, an ABS system, a TPMS setup, or just about any other piece of motorsport electronics, there's a good chance we asked you a question that seemed completely unrelated to what you were trying to buy.

"What ECU are you running?"

Then: "What CAN bus are you connecting to?"

Then: "What baud rate is that bus running?"

And eventually, something like: "What exactly are you trying to make these two systems do?"

There's a reason for all of it. Modern race cars lean heavily on CAN bus to move information between the ECU, dash, ABS, TPMS, sensors, and everything else. Done right, CAN makes a car's electronics dramatically more capable without a dedicated wire for every signal. Done wrong, you end up with an expensive pile of electronics that don't talk to each other the way you expected.

So let's make CAN a little less intimidating.

What CAN Bus Actually Is

CAN stands for Controller Area Network. It was developed for the automotive industry decades ago, and it's since become the standard way motorsport electronics talk to each other.

Instead of running a dedicated wire from an oil pressure sensor to the dash, another wire from the ECU to the logger, and another set from the ABS system to the dash, CAN lets every device share one network. At the physical level, a standard high speed CAN network runs on two wires, CAN High (typically white or yellow) and CAN Low (typically green), twisted together to cancel out electromagnetic interference and prevent data errors.


The system reads the voltage difference between the two, which is a big part of why CAN holds up so well in an electrically noisy race car.

But the wires themselves aren't really the interesting part. It's what they carry. A CAN device doesn't just dump data onto the network. It sends structured messages, and any other device on the bus that's configured to understand a given message can pick it up and use it. Your dash doesn't need its own dedicated wire from the wheel speed sensors. It just needs to be on the same bus as whatever device is already reading them.

That's why a modern race car with dozens of sensors doesn't need dozens of individual wire runs threading through the chassis. It's worth being clear on one physical detail here too: every device on the network taps both CAN High and CAN Low. There's no such thing as a device that only connects to one side of the pair, the differential signal needs both wires to mean anything at all.

CAN Doesn't Automatically Mean Everything Works Together

This is probably the single most misunderstood part of CAN, and it's worth getting out of the way early. Two devices both having CAN does not mean they'll automatically communicate.

CAN is the transport. The devices still have to agree on what the messages actually mean. Think of it like two people who both speak English but don't share the same technical vocabulary. A CAN message carries an ID, a set of data fields, and a scaling factor, and the receiving device needs to know how to read all of it. If one device sends a raw value of 500, the receiving system needs to already know whether that means 500 psi, 50.0 psi, 500°C, or something else entirely.

That's why "it has CAN" isn't really an answer to whether two products will work together, and it's a big part of why we ask so many questions before recommending a part.

Why It Matters for Wiring, Not Just Data

Take a TireWatch/OnRace TPMS receiver. The RCU outputs tire pressure and temperature over CAN. Wired as a CAN device, that data doesn't need its own dedicated run all the way to your dash or logger. It just joins the same bus everything else is already using. We cover the RCU and the rest of the TireWatch (OnRace) lineup in our TPMS buyer's guide, and the CAN output option is a big reason it's easy to integrate into an existing system.

The VBOX HD2 shows the other side of it. It doesn't need CAN at all to function. GPS alone gives you speed, position, and lap timing right out of the box. But wire it into the car's CAN bus, and it starts picking up channels like brake pressure and throttle position that are already flowing across the network, without adding a single new sensor. It's simply listening.

CAN Speed Is a Real Decision, Not a Detail

CAN bus has a speed, usually called the baud rate, and it isn't just a spec sheet footnote. In motorsport, the two speeds you'll run into most often are 500 kbit/s and 1 Mbit/s, and every device sharing a physical bus segment has to run at the same one. Mix speeds on a single segment and the devices won't understand each other, full stop.

This is a real spec question we deal with constantly, not a theoretical one. The Bosch Motorsport M5 ABS kit is configured for either 500 kbt/s or 1 Mb/s, and the wheel speed sensor variant it ships with (DF11S, DF11I, or DF11V) has to match whichever speed the car's bus is running. Get that wrong and the ABS unit won't communicate properly with the rest of the car. It's why, as an Authorized Bosch Motorsport ABS Dealer, we confirm CAN bus speed and sensor type with every customer before a kit ships, rather than treating it as an afterthought.

The same question comes up with nearly anything CAN based you add to a car. Before we recommend a sensor, a module, or a dash, one of the first things we ask is what speed the existing bus is running, because that answer often decides which parts actually fit.

One Car, More Than One Bus

A car doesn't have to run just one CAN network, and as the amount of data on a car grows, one network often isn't enough. CAN bandwidth is finite, and the more devices and messages you put on a single bus, the more traffic it has to carry.

The MoTeC C127 is a good example of the solution. It has two separate CAN buses, and each one can be set to its own speed independently. A common setup keeps the ECU and other high priority, high frequency traffic on one bus, and puts slower devices like a TPMS receiver on a second bus running at a different speed. That keeps the primary bus from getting overloaded, and it means a fault or a marginal connection on one bus doesn't necessarily take down the other. The C127 sits in the middle of both networks, reading from each and displaying or logging whatever you've configured it to.

Bringing Analog Sensors Into a CAN System

Not every sensor speaks CAN natively, and plenty of proven analog sensors, along with plenty of older chassis, are built around a simple voltage output instead. Rather than running a dedicated analog wire from a sensor all the way to the dash, a module like AvioRace's 4 Analog to CAN Bus Module takes up to four analog inputs, things like brake or tire temperature sensors, and converts them into proper CAN messages that go straight onto the bus with everything else.

This comes up a lot on resto-mod builds and older cars that weren't designed around a CAN network in the first place. You get the wiring benefit of CAN without needing every sensor on the car to be CAN native from the factory.

When CAN Isn't Working

CAN problems don't always look like CAN problems. A dash that powers up but shows no engine data, an ABS system that won't communicate, a TPMS system that works fine on its own but never shows up on the dash, missing channels in a logger. None of that necessarily points to a bad device.

More often it's something in the setup: CAN High and Low wired backwards, a baud rate mismatch, a missing or duplicated termination resistor, or two devices fighting over the same message ID. High speed CAN needs a 120 ohm resistor at each physical end of the bus, no more and no less, and it's one of the more common things we find missing or doubled up when we're helping someone troubleshoot a system that "should" be working.

This Is Why We Ask So Many Questions

If you've ever called us and thought, why are they asking me all of this, I just want a sensor, this is why. Before we recommend a CAN device, we usually need to know what ECU and dash or logger you're running, which bus you're connecting to and at what speed, what's already on that bus, and what you're actually trying to accomplish with the new data.

That isn't us making it harder to buy a part. It's us making sure the part you buy actually works in the system you're building. The more you can tell us up front, the faster we can get you to the right answer.

The Bottom Line

CAN bus is what lets a modern race car's electronics talk to each other over two wires instead of dozens. But having CAN in common isn't the same as being compatible, and getting a system right means matching bus speed, wiring it correctly, terminating it properly, and making sure every device agrees on what its messages mean.

When you're planning a build, it helps to start with the actual question rather than the part number. Not "what sensor do I need," but what measurement you're actually after. Not "which dash has the biggest screen," but what information the driver needs to see and what networks the dash has to talk to. Once you know that, choosing the hardware gets a lot easier, and if you don't know the answers yet, get in touch and we'll help you work through it before you buy the wrong parts.

Frequently Asked Questions