AutoCodes – Generic – C1221

C1221 Code - Left Front Wheel Speed Sensor Input Signal Is Zero

Quick Answer

As the wheel spins, the wheel speed sensor produces an AC signal. Common causes include Faulty Hub Assembly (Left Front Wheel Speed Sensor is part of hub assembly), Faulty Left Front Wheel Speed Sensor, Left Front Wheel Speed Sensor harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: C1221 indicates Left Front Wheel Speed Sensor Input Signal Is Zero.
Common causes: Common causes include Faulty Hub Assembly (Left Front Wheel Speed Sensor is part of hub assembly), Faulty Left Front Wheel Speed Sensor, Left Front Wheel Speed Sensor harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 37,390

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 26, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code C1221 Description

As the wheel spins, the wheel speed sensor produces an AC signal. The Electronic Brake Control Module (EBCM) uses the frequency of the AC signal to calculate the wheel speed. The EBCM will set the OBDII code when the sensor is not to factory specifications.

OBDII Code C1221 - Left Front Wheel Speed Sensor Input Signal Is Zero - AutoCodes.com — C1221 Code - Left Front Wheel Speed Sensor Input Signal Is Zero

What does this mean?

What are the Possible Causes of the DTC C1221?

Faulty Hub Assembly (Left Front Wheel Speed Sensor is part of hub assembly)
Faulty Left Front Wheel Speed Sensor
Left Front Wheel Speed Sensor harness is open or shorted
Left Front Wheel Speed Sensor circuit poor electrical connection

How to Fix the DTC C1221?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C1221 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the C1221 code?

Need more information on how to fix the C1221 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C1221 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C1221 Buick — Left Front Wheel Speed Sensor Input Signal Is Zero
C1221 Cadillac — Left Front Wheel Speed Sensor Input Signal Is Zero
C1221 Chevrolet — Left Front Wheel Speed Sensor Input Signal Is Zero
C1221 GMC — Left Front Wheel Speed Sensor Input Signal Is Zero
C1221 Pontiac — Left Front Wheel Speed Sensor Input Signal Is Zero

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about C1221 Code

1. What are the common symptoms of OBDII code C1221 (Left Front Wheel Speed Sensor Input Signal Is Zero)?

- Common symptoms include the ABS warning light illuminated on the dashboard, traction control system malfunction, and potential loss of ABS functionality.

2. What are possible causes of OBDII code C1221?

- Possible causes include a faulty left front wheel speed sensor, damaged wiring or connectors in the sensor circuit, or a malfunctioning ABS module.

3. How can I diagnose the cause of OBDII code C1221?

- You can diagnose the cause by performing a visual inspection of the sensor and its wiring, testing the sensor with a multimeter, and using a scan tool to monitor wheel speed sensor data while driving.

4. Can a dirty or obstructed wheel speed sensor cause code C1221?

- Yes, debris or dirt buildup on the sensor can disrupt its signal and trigger code C1221. Cleaning the sensor may resolve the issue.

5. What are some repair tips for resolving OBDII code C1221?

- Repair tips include checking and cleaning the sensor and its connectors, repairing damaged wiring, replacing a faulty sensor, or reprogramming the ABS module if necessary.

6. Is it safe to drive with OBDII code C1221 present?

- It is not recommended to drive with code C1221 active, as it can affect the proper functioning of the ABS system and compromise vehicle safety.

7. Can I reset OBDII code C1221 without fixing the underlying issue?

- While you can clear the code temporarily, it is crucial to address the root cause to prevent the issue from reoccurring and ensure the ABS system operates correctly.

8. How much does it typically cost to repair OBDII code C1221?

- The cost of repair can vary depending on the cause of the issue and labor rates, but it may involve replacing the wheel speed sensor, repairing wiring, or reprogramming the ABS module.

9. Will OBDII code C1221 cause a vehicle to fail an emissions test?

- Code C1221 is related to the ABS system and may not directly affect emissions, but it is still important to address and resolve the issue to ensure overall vehicle safety and performance.

10. Can a DIY enthusiast repair OBDII code C1221 at home?

- Depending on the cause, DIY enthusiasts with the necessary tools and knowledge may be able to address code C1221 by replacing the wheel speed sensor or repairing wiring themselves.