Check Engine or ABS Light Wheel Speed Sensor Circuit Open - Code C0221

So you have an ABS light that came on on your dash and you scan it and you have a C0221. Let's try to figure out what's going on.

So that code is related to this. This is a wheel speed sensor and a hub. Now, this is what holds the wheel. It attaches it to the car. And on the hub has the sensor, and this is probably what's going on. This is probably what's causing the code.

The first quick and easy thing you can check is the wheel speed sensor itself. Just take a look at it, make sure you don't see any cuts in the wire. Now, if you look over here on this side, now this is where the wire is gonna flex. Every time you turn the wheel, this wire is gonna bend back and forth, back and forth. And over time they're gonna break. They could break internally so you can't even tell that it's broken on the outside, or you might be able to tell.

And then follow that wire all the way up here to the connector and just make sure the connector is tight. It's pretty unlikely that the connector is gonna be loose like that, but it's always a good idea to check. Make sure that's on there good, locked in place. So with it disconnected, you're gonna want to look at both sides on this side and also the wheel speed sensor side and make sure you don't see any corrosion in there. Now, what I mean by corrosion, make sure there's nothing that's green or blue or anything. If it looks shiny and it's metal, that's gonna be okay, but if you see blue or green, that's not gonna be good. There's moisture getting in there and that could cause this issue.

So whether you have corrosion in there, or whether you have a break in the wire or even there's something messed up with the sensor itself, you're gonna have to replace the whole sensor. You can't repair the wires. It's really not a good idea to replace the connector. To disconnect the sensor itself, you want to take this bolt out and be very careful when removing it. A lot of times, they get stuck in there and you just gotta be careful. You don't want it to break in the hub itself because then you might have to drill, it might be more of an issue. You may even have to replace the whole hub, but you're gonna do that to replace the sensor.

So we're talking about a wheel speed sensor. What does that have to do with ABS at all? ABS stands for Anti-lock Brake System and it's there to help you control the vehicle during slippery situations. So as the wheels are spinning, all four wheels are sending signals through those wheel speed sensors and it's going over here to the ABS module, which is the computer or the brain of the system. And when it notices that one of those sensors is bad, it's gonna set that ABS light.

Now, if you didn't see anything visually wrong with the wheel speed sensor, the next thing we're gonna do is we're gonna use a multimeter to test the wheel speed sensor. Basically, what this meter is gonna do is on one side of the circuit, one of the wires, it's gonna send power down this wire, very low voltage, and then it's gonna go through the sensor and then out the other side. And then we're gonna measure the other side and that's gonna give us a number and we need that number to be in between a specific range. And if that number is not in that range, then that sensor is bad.

So we're gonna take the meter and we're gonna put it on the ohms setting. It looks like a little horseshoe. And one side is gonna send voltage and the other side is gonna read that voltage and put them together, you're going to get a number. And basically if you think of measuring a wire with these two as like a hose, like if you have a typical garden hose, it's gonna have so much water going through it. And the difference would be a hose like a fireman's hose. It's gonna be a lot more water. So there's going to be a lot more current that goes through it. So the same with wires. Thinner wires are gonna have less current, thicker wires are gonna have more. So that's what we're measuring. So we'll send one on one side and it doesn't matter which side you go and then check it with the other side. And there's our reading. And it's 1 kiloohm which is 1,000 ohms. Well, 1,075. Now with our reading for this actual wheel speed sensor, it should be between 700 and 10,000 ohms. So that's within spec. Now that's for this vehicle. It's not for every vehicle. Other vehicles may be different. And if you didn't know, what you could do is go up to the other sensors and just see if they're significantly different. So here's another wheel speed sensor. Do the same thing and just see if they're very close. And that's pretty much 1,000 ohms right there. So you would know that these are pretty close to the same readings. And if you went to all four, then you could get a rough idea of what it should be.

So if we did the same test and we ended up with 500 ohms, that would have been out of the range, the wheel speed sensor would have been bad. And same with if it said OL, which means the circuit is open. Like these are not touching each other. There would be something broken in there. The wheel speed sensor would be bad.

Now have the meter hooked up to the wheel speed sensor and we're gonna switch to voltage, but alternating current, AC voltage, not DC voltage. And as we're monitoring this, we're gonna spin the wheel and we should see over 100 millivolts, which we do. Now, every vehicle is gonna be a little bit different. That's just the setting for this vehicle. If you don't know what the spec is, you can look it up, do your research online, or you can check the other wheel speed sensors and see what they're putting out. And if it's significantly different, then the wheel speed sensor is probably bad.

So one more thing before you just go and replace the wheel speed sensor. Inside the wheel hub itself, there is a ring with teeth on it. It's called a tone ring or a reluctor wheel. What this is going to do is this is what the sensor is gonna look for as it turns. So if the hub has something wrong with it, there's play in the hub or something happened to that ring where it broke off and isn't able to move or spin, then that could be another issue. So you want to check out the hub itself before you just replace the sensor.

So you want to raise the vehicle and put your hand on the top of the tire and also the bottom of the tire and you're gonna shake the wheel back and forth. So push in while you pull out and vice versa. And if there's any significant play there, then that hub's probably going to need to be replaced. And normally that hub will come with the new sensor.

Now, another thing you could do if you didn't have that test equipment, you didn't have a meter, what you could do is take the wheel speed sensor out of this side and swap it and then drive the vehicle around and see if your code actually moved with the wheel. Then you definitely know you need a wheel speed sensor.

So let's say you were testing all that stuff and everything passed the test, it could be something in the wiring that goes to the ABS module or the ABS module itself.

So if you have a C0221, there's some simple tests you can do to figure out the problem. I hope you enjoyed this video. If you did, please subscribe to our channel. Make sure you ring that bell, turn on all notifications so you don't miss any of our videos.