Engine-Codes - Generic - C0021

C0021 Code - Brake Booster Performance

- Code Popularity: 24,194 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents
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What are the Possible Causes of the DTC C0021?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Brake Booster
  • Faulty Vacuum Pressure Sensor
  • Vacuum Pressure Sensor harness is open or shorted
  • Vacuum Pressure Sensor circuit poor electrical connection
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How to Fix the DTC C0021?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the C0021 code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Anti-Lock Brake System (ABS) Warning Light ON
  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the C0021 Code Mean?

When the Vacuum Pressure Sensor indicates a failure in the Vacuum Booster. After the cold start phase (i.e. 3 min after engine is running) and if the engine is running above 600 RPM there should be at least -200 mbar (-2.90 psi) of differential pressure in the vacuum-chamber for boosting the pedal force. If the pressure remains below this value for more than two minutes. Timer resets if the pressure remains above 220 mbar (3.19 psi) for 10 seconds.

C0021 Code - Brake Booster Performance

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Code C0021 Information for Specific Makes

  • C0021 Buick Right Front Wheel Speed Sensor Circuit Open Or Shorted To Battery
  • C0021 Cadillac Right Front Wheel Speed Sensor Circuit Open Or Shorted To Battery
  • C0021 Chevrolet Right Front Wheel Speed Sensor Circuit Open Or Shorted To Battery
  • C0021 Chrysler Brake Booster Performance
  • C0021 Dodge Brake Booster Performance
  • C0021 GMC Right Front Wheel Speed Sensor Circuit Open Or Shorted To Battery
  • C0021 Jeep Brake Booster Performance
  • C0021 Subaru Front Right ABS Sensor Circuit Open Or Short

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