C0035 is a manufacturer-specific chassis trouble code that can occur in the Opel Insignia. GM designated C0035 to indicate an issue with the left front wheel speed sensor.
Replacing your Insignia’s left front wheel speed sensor is the most common fix for C0035, but it’s not the only one.
C0035 Definition
C0035: Left Front Wheel Speed Sensor
C0035 indicates that your Insignia’s left front wheel sensor is malfunctioning. Here’s the 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 Opel 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 your Insignia’s drivers 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. The Opel Insignia uses that data to determine if one of its wheels 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 your Insignia’s 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.
Opel Insignia C0035 Symptoms
Since this is a chassis code, there’s no risk of your Insignia’s engine breaking down with it. 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
Opel Insignia C0035: Causes and Diagnosis
Here are the most common causes of C0035 in the Opel Insignia, and a good order to diagnose them in:
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” or more pullable (very gently) 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 Opel. You can get these directly from the NTSB website: https://www.nhtsa.gov/recalls
You can search by VIN or by model year.
These bulletins detail problems known to GM about the Insignia, 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. Good luck repairing your Insignia!