C0035 is a manufacturer specific chassis-related trouble code. GM designated C0035 to indicate an issue with the left front wheel speed sensor. Replacing the left front wheel speed sensor is the most common fix for C0035, but it’s not the only one.
C0035 Meaning
C0035: Left Front Wheel Speed Sensor
C0035 indicates that the left front wheel sensor is malfunctioning. Here’s its definition, broken down into three parts:
Left Front
Even if you are a pretty experienced shade tree mechanic, you may wonder which side of the vehicle GM considers the “left front.”
Auto manufacturers use left and right instead of “passenger” and “driver” since the side of the vehicle people drive on can change depending on what part of the world they live in.
LF is determined by where it is in relation to you when sitting in the driver’s seat. So, the “left front” is the wheel that’s ahead of you and to the left.
Wheel Speed Sensor
Wheel speed sensors measure how fast each wheel is turning. Your vehicle uses that data to determine if the vehicle has broken traction, or if the brakes have locked up.
The wheel speed sensors help the ABS module determine if one of the wheels has broken traction. If your vehicle has traction control, that system uses the wheel speed sensors as well.
Qualifiers
There can be qualifiers at the end of the code that can help you further determine what is going on with the wheel speed sensor.
For example:
- C0035-00: Left Front Wheel Speed Sensor Circuit
- C0035-0F: Left Front Wheel Speed Sensor Signal Eratic
If you get the 0F version of this code, you’d definitely want to start by taking a look at the wiring harness coming from the left front wheel speed sensor. Or, if you have a good scan tool, you can look at the signal waves coming from the LF wheel speed sensor and compare the values to the RF wheel speed sensor.
C0035 Symptoms
Since this is a chassis code, it is not a breakdown risk. But, ABS and traction control are important safety features. Here are the most common C0035 symptoms:
- Check engine light
- ABS system inactive (ABS light)
- Traction control disabled
C0035 Causes and Diagnosis
Here are the most common causes of C0035, and a good order to diagnose them:
Wheel Speed Sensor Wiring
Check the wiring harness going to the left front wheel speed sensor. Is it damaged in any way? This is a very common cause of C0035. You’ll be looking for cracked, burnt, or frayed wires.
The wiring can go bad even without breaking. It’ll be “floppier” than the rest of the wiring in the harness. You can see exactly what that looks like in the video below.
Wheel Speed Sensor
Replacing the wheel speed sensor is the most common repair when you get C0035.
Wheel speed sensors can and do go bad. They can also get too grimy to do their job. Sometimes cleaning them will clear the code.
Technical Service Bulletins
TSBs are repair information that comes directly from the manufacturer. You can get these directly from the NTSB website: https://www.nhtsa.gov/recalls
These bulletins detail problems known to GM about a particular model vehicle, and the common repair steps. Even if there is a TSB related to your vehicle, it will still often end up being the wheel speed sensor that is causing C0035.
Conclusion
The most common cause of C0035 is a bad wheel speed sensor.