Wheel Speed Sensor Circuit Malfunction (Left Front)
Indicates a problem with the left front wheel speed sensor circuit.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The left front wheel speed sensor is sending the wrong signals or has stopped sending signals to the computer, which can affect anti-lock brakes and traction control.
What the computer is actually seeing
The ABS module expects a voltage signal from the left front wheel speed sensor that varies based on wheel speed. Typically, this should range from 0 to 5 volts, with a frequency change as the wheel rotates.
What a healthy reading looks like
Voltage should be between 0.1V and 4.5V when the vehicle moves. Above 5V indicates a problem; below 0.1V indicates a fault.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the left front wheel speed sensor for physical damage or debris.
- 22. Check the wiring and connectors for corrosion, breaks, or poor connections.
- 33. With the ignition on, use a scanner to monitor the voltage of the left front wheel speed sensor. Expected voltage is between 0.1V and 4.5V when the wheel is spinning.
- 44. If the voltage is out of range, replace the left front wheel speed sensor and retest.
- 55. If the sensor is good, check the ABS module for faults, searching for ground issues or internal errors.
Common causes
- Damaged wheel speed sensor
- Corroded wiring or connectors
- Faulty ABS module
- Brake system interference or damage
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with code C1420?
It's drivable but you may have reduced braking performance and issues with traction control. Fix it soon.
Will this code come back after clearing it?
If the underlying issue isn’t resolved, the code will likely return after clearing.
Why does this code appear with other codes?
Multiple codes can indicate electrical issues or sensor failures affecting the whole system.
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