If your check engine light comes on and you get a C0040 code (or maybe even an ABS light). It means that one of the wheel speed monitors that sends data to the ABS system is faulty.
This problem can be scary because it’s harder to stop safely when the ABS isn’t working. Find out what can cause a C0040 code, how important it really is, and how to fix it below.
What does the C0040 Code mean?
Diagnostic error C0040 code means that the wheel speed sensor on the front right wheel is broke (Code C0035 would mean the same thing for the front left wheel). Or that the circuit that controls it is in damage in some other way.
To put it simply, the car’s ABS Sensor has found that the right-front speed sensor’s feedback is irrational, erratic, or nonexistent, which means the situation is not as expected.
Each of a car’s four-wheel speed sensors sends feedback to make sure that safety systems like anti-lock brakes and stability control are working properly. In more specific terms, this input is used to find individual wheel lock-up or spin. Which in the context of these safety systems means that something needs to be done.
When there is a problem with a wheel speed sensor. Most safety systems in cars, like ABS and stability control, stop working. This is to protect the systems’ integrity.
This makes sure that these systems won’t react wrongly to wrong wheel speed data. Because of this, when DTC C0040 is records, ABS and traction control usually stop working.
C0040 Code Symptoms
Most of the time, diagnostic fault code C0040 comes with a number of different symptoms. Some of which are more obvious than others. If you want to speed up the whole testing process, learning to spot these signs can be very helpful.
These are the most usual signs that you might have DTC C0040.
- ABS light with an LED
- Traction control light could be on
- Not having an ABS system
Causes of C0040 Code
The diagnostic fault code C0040 could be caused by a number of different problems, most of which have to do with the circuit that is affected by the wheel speed sensor. If you want to fix something quickly, knowing about these possible reasons can make all the difference.
It’s possible that one of these things is causing DTC C0040.
- A broken speed monitor
- Wheel speed sensor reluctor wheel damage
- Problems with the wheel speed sensor circuit
- ABS part that is faulty
Is Code C0040 Serious?
In general, diagnostic fault code C0040 is thought to be of mild severity. When this trouble code record occur, it won’t stop you from driving your car, but it does mean that there is a problem that needs to be looked at more closely and fixed.
So, you shouldn’t ignore your car’s C0040 fault just because it doesn’t affect how well it drives overall.
It’s also important to remember that if any kind of ABS fault code is present, the ABS system will not work at all, including C0040 Code. So, a car’s ABS won’t work again until the cause of DTC C0040 is found and fixed.
Additionally, in some situations, extra safety systems that use wheel speed sensor input, like traction control, will also be turned off.
In any case, you can find root cause and fixed right away to keep the car safe to drive. You should make an appointment right away with a qualified car repair shop if you don’t know how to troubleshoot and fix this problem yourself. If you let electricity problems in important steering parts last for a long time, they will usually get worse.
How to Fix the C0040 Code Error
There are steps you can take to help you figure out what caused your car’s C0040 diagnostic fault code and fix it. Before you try to fix anything, you should always look at the factory-specific service literature for your type of car.
1: Check for more trouble codes.
Use a good OBD2 scan tool to see if there are any other diagnostic fault codes before you start the diagnostic process. If these kinds of codes occur, carefully analyze before moving on.
2: Check the wiring and wheel speed sensor
In order to start the troubleshooting process, carefully look at the wheel speed sensor damage. where it is mounted in the wheel hub of the vehicle. You might not be able to look at the sensor in its entirety, but you can make sure it is still in the hub and not damaged in any way.
Also, all the wiring that goes to the wheel speed monitor should be checked for signs of damage, fraying, or binding. You would have to replace it if it was damage in any way.
3: Check the Hub Reluctor Wheel
Next, you will need to check the right front wheel hub of the car for damage to the reluctor wheel. To get a clear look of the reluctor wheel, take off the hub’s wheel speed sensor at the very least.
The front of the car can be raised, which lets you spin the front wheels by hand. Jack stands must always be used for this. If there is damage to the reluctor wheel, the hub will need to be replaced.
4. Check the play in the wheel bearings
While the damaged vehicle’s front end is raised, you should also check the right front wheel end for too much wheel bearing play.
To do this, hold the wheel here at 12 o’clock and 6 o’clock and try to move it from inside to outside. Any kind of play that can measure will need a new hub.
5: Check the WSS sign
If there are no problems so far, you should use a good scan tool to look at all the information from the right-front wheel speed monitor. This feedback should be smooth and steady, with no dead spots at high speeds. It should also show that the pulses are getting stronger as the car speeds up overall.
If that’s not the case, it means the speed monitor or the wiring that connects to it is faulty. If all of the tests come back within the range given by the maker. Then you will need more testing to rule out any problems with the ABS module.
Before throwing out a car’s ABS unit, all of the suggested manufacturers steps should be taken. A new one isn’t cheap.
