ABS Pressure Sensor Circuit Low
The C0021 code means the vehicle's onboard diagnostic system has detected: ABS Pressure Sensor Circuit Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $150 - $600 (parts and labor)
Basic scanners cannot read ABS codes. BlueDriver reads all systems including ABS, SRS, and transmission through your phone.
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Basic scanners cannot read ABS codes. This one reads all four systems so you know exactly which sensor failed.
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Common Symptoms
- ABS warning light on
- Spongy brake pedal
- ABS activates too easily
- Traction control malfunction
Probable Causes (Ranked by Likelihood)
- Failed ABS pressure sensor reading low Very High
- Low brake fluid level High
- Air in ABS hydraulic system Moderate
- Leaking ABS hydraulic line Low
Step-by-Step Diagnostic Procedure
-
Check brake fluid level at master cylinder
-
Monitor pressure sensor readings at rest and during braking
-
Inspect ABS hydraulic lines for leaks
-
Bleed ABS system and retest
Frequently Asked Questions
Why is the ABS pressure reading low?
Low brake fluid, air in the system, a leak, or a faulty sensor can cause low pressure readings.
Can I just add brake fluid to fix this?
Adding fluid may help if low level was the cause, but low fluid usually indicates a leak or worn pads.
Is low ABS pressure dangerous?
While standard brakes still work, ABS effectiveness is reduced.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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