AutoCodes – Ford – C109F Ford

C109F Ford Code - Vacuum Sensor Signal Fault

Quick Answer

The vacuum sensor is used by the Anti-Lock Brake System (ABS) Module to determine if hydraulic pump intervention is necessary due to loss of vacuum in the booster. Common causes include Loose Brake Booster Vacuum Hose, Faulty Brake Booster Vacuum Sensor, Brake Booster Vacuum 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: C109F Ford indicates Vacuum Sensor Signal Fault.
Common causes: Common causes include Loose Brake Booster Vacuum Hose, Faulty Brake Booster Vacuum Sensor, Brake Booster Vacuum 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.

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Code Popularity 7,032

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 12, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C109F Ford Description

The vacuum sensor is used by the Anti-Lock Brake System (ABS) Module to determine if hydraulic pump intervention is necessary due to loss of vacuum in the booster. The ABS module sends a 5-volt reference voltage to the sensor, the sensor compares the pressure in the booster to the ambient air pressure in the engine compartment and sends a varying voltage back to the ABS module based on the difference between the pressures. Normally, the pressure in the booster is much lower than ambient air pressure. As the pressure in the booster gets higher (closer to matching ambient air pressure), the lower the voltage sent back to the ABS module becomes.
When the vacuum in the brake booster falls below a predetermined level, the ABS module will command the hydraulic pump motor to activate on the next (and any subsequent) brake pedal application to assist with vehicle braking. The ABS module will continue to use the pump motor for braking assist as long as the low vacuum condition exists.

OBDII Code C109F Ford - Vacuum Sensor Signal Fault - AutoCodes.com — C109F Ford Code - Vacuum Sensor Signal Fault

What does this mean?

What are the Possible Causes of the DTC C109F Ford?

Loose Brake Booster Vacuum Hose
Faulty Brake Booster Vacuum Sensor
Brake Booster Vacuum Sensor harness is open or shorted
Brake Booster Vacuum Sensor circuit poor electrical connection

How to Fix the DTC C109F Ford?

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 C109F Ford 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.

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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 C109F Ford Code

1. What are the common symptoms of OBDII code C109F Ford (Vacuum Sensor Signal Fault)?

- Common symptoms include rough idling, engine hesitation, decreased fuel efficiency, and potential stalling.

2. What could cause the OBDII code C109F Ford to trigger?

- The code may be triggered by a faulty vacuum sensor, vacuum leak, wiring issues, or a problem with the engine control module.

3. How can I diagnose the Vacuum Sensor Signal Fault related to code C109F in a Ford vehicle?

- To diagnose the issue, you may need to use a scan tool to read the code, check the vacuum sensor for proper operation, inspect vacuum lines for leaks, and test the wiring for continuity.

4. Are there any DIY repair tips for resolving the Vacuum Sensor Signal Fault in a Ford vehicle?

- DIY repair tips include checking and replacing damaged vacuum lines, cleaning the vacuum sensor, ensuring proper wiring connections, and resetting the fault code with a scan tool.

5. Can a Vacuum Sensor Signal Fault lead to other problems in the vehicle?

- Yes, if left unresolved, a Vacuum Sensor Signal Fault can lead to poor engine performance, potential damage to engine components, and increased emissions.

6. Is it safe to drive with the OBDII code C109F Ford (Vacuum Sensor Signal Fault) present?

- It is generally not recommended to drive with the fault code present, as it can impact the vehicle's performance and may cause further damage if ignored.

7. How much does it typically cost to repair the Vacuum Sensor Signal Fault in a Ford vehicle?

- The cost of repair can vary depending on the exact cause of the fault, but it may range from $100 to $300 for parts and labor.

8. Can resetting the fault code make the Vacuum Sensor Signal Fault disappear permanently?

- Resetting the fault code may temporarily clear the code, but if the underlying issue is not addressed, the fault code is likely to reappear.

9. Is it necessary to visit a dealership or mechanic to repair the Vacuum Sensor Signal Fault?

- While professional help is recommended for accurate diagnosis and repair, some DIY enthusiasts may be able to resolve the issue with proper tools and knowledge.

10. How can I prevent the OBDII code C109F Ford (Vacuum Sensor Signal Fault) from reoccurring?

- Regularly inspecting and maintaining the vacuum system, addressing any vacuum leaks promptly, and ensuring proper sensor function can help prevent the fault code from reoccurring.