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Code C0561

Symptoms

• Check Engine Light illuminated

• Poor engine performance

• Increased fuel consumption

Common Causes

• Faulty vacuum sensor

• Vacuum leak in the intake manifold

• Wiring issues or poor electrical connections

Glossary

Vacuum Sensor: A device that measures the vacuum pressure in the engine's intake manifold.

ECU: Engine Control Unit, the computer that manages engine functions.

Related Codes

• P0106

• P0107

Laymans terms

This code means that the car's computer found a problem with the vacuum sensors, which help the car know how much air is being sucked into the engine. It's like when you have two straws and they don't suck the same amount of juice, the car gets confused.

Explanation

The C0561 code is triggered when the vehicle's control module detects a mismatch or correlation error between two vacuum sensors, labeled A and B.

Technical description

The vacuum sensors are responsible for measuring the vacuum pressure in the intake manifold. This information is crucial for the engine control unit (ECU) to adjust the air-fuel mixture and ensure optimal engine performance. When the readings from Vacuum Sensor A and Vacuum Sensor B do not match within a specified range, the C0561 code is set.

Diagnosis steps

• Use an OBD-II scanner to confirm the C0561 code.

• Inspect vacuum hoses and connections for leaks or damage.

• Test the vacuum sensors for proper operation and signal output.

Repair procedures

• Replace faulty vacuum sensors.

• Repair or replace damaged vacuum hoses.

• Fix any wiring or connection issues.

Tools required

• OBD-II scanner

• Multimeter

• Vacuum pump

Estimated repair cost

$100 - $300

Difficulty level

Moderate

Commonly affected vehicles

• Chevrolet Silverado

• GMC Sierra

• Cadillac Escalade

Preventive measures

• Regularly inspect vacuum hoses for wear and tear.

• Ensure proper maintenance of the intake system.

• Check electrical connections periodically.

Error code type

Sensor Issue

User experience recommendations

• Address the issue promptly to avoid further engine problems.

• Consult a professional mechanic if unsure about the repair process.

Warranty information

Check with the vehicle manufacturer for specific warranty coverage related to sensors.

Historical data

The C0561 code has been associated with vehicles that have had issues with vacuum sensor reliability, especially in older models.

Urgency level

Moderate – It is important to address this issue to maintain engine performance and efficiency.

Legal and safety notice

Operating a vehicle with a malfunctioning vacuum sensor can lead to increased emissions and may not comply with local vehicle emission laws.

Testing conditions

• Engine running at idle

• Vehicle at operating temperature

Component location

The vacuum sensors are typically located near the intake manifold of the engine.

FAQs

Q: What happens if I ignore the C0561 code?
A: Ignoring this code can lead to poor engine performance and increased fuel consumption.

Q: Can I drive with a C0561 code?
A: While the car may still be drivable, it's best to fix the issue to avoid potential engine damage.

Last updated: Jun 8, 2026 • Source: internal database
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