Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there is a problem with the car's brake system. The part that helps the brakes work by creating a vacuum isn't working right.
The C1042 code is triggered when the brake system vacuum pump control circuit is detected to have low voltage or is not functioning as expected.
The brake system vacuum pump is responsible for providing the necessary vacuum pressure to assist the braking system. The control circuit monitors and regulates the operation of this pump. A 'low' condition indicates that the circuit is not receiving enough voltage, which could affect the pump's performance.
• Reduced braking performance
• Brake warning light on the dashboard
• Unusual noises from the brake system
• Faulty vacuum pump
• Damaged wiring or connectors in the control circuit
• Blown fuse or relay associated with the vacuum pump
Vacuum Pump: A device that removes air to create a vacuum.
Brake Booster: A component that uses vacuum pressure to assist the driver in applying the brakes.
• Inspect the vacuum pump for any visible damage.
• Check the wiring and connectors for signs of wear or damage.
• Test the voltage and continuity of the control circuit.
• Replace the faulty vacuum pump.
• Repair or replace damaged wiring or connectors.
• Replace any blown fuses or faulty relays.
• Multimeter
• OBD-II scanner
• Basic hand tools
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regular maintenance checks on the brake system.
• Ensure electrical connections are secure and free from corrosion.
• Replace worn-out components promptly.
Sensor Issue
• Do not ignore the brake warning light.
• Have your vehicle inspected by a professional if you notice braking issues.
Check with your vehicle manufacturer for specific warranty coverage on brake system components.
This code has been associated with vehicles that have electronic braking systems and vacuum-assisted brakes.
High – Brake system issues can affect vehicle safety and should be addressed immediately.
Driving with a malfunctioning brake system can be dangerous and may violate traffic safety regulations.
• Vehicle must be running.
• Brake system should be engaged to test the vacuum pump operation.
The vacuum pump is usually located near the brake booster in the engine compartment.
Q: Can I drive with a C1042 code?
A: It's not recommended as it may compromise braking performance.
Q: How do I reset the C1042 code?
A: Fix the underlying issue first, then use an OBD-II scanner to clear the code.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
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Universal · Drive-on ramps
Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
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