C109E Code - Vacuum Sensor Circuit 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
- C109E indicates Vacuum Sensor Circuit 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.
Code C109E Description
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.
What are the Possible Causes of the DTC C109E?
- 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 C109E?
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 C109E 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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Information for Specific Makes
- C109E Ford — Vacuum Sensor Circuit Fault
- C109E Lincoln — Vacuum Sensor Circuit Fault
- C109E Mercury — Vacuum Sensor Circuit Fault
Frequently Asked Questions about C109E Code
1. What are the common symptoms of OBDII code C109E (Vacuum Sensor Circuit Fault)?
- Common symptoms include poor engine performance, rough idling, decreased fuel efficiency, and potential stalling.
2. What causes the OBDII code C109E to trigger?
- The code is typically triggered by a faulty vacuum sensor, damaged wiring/connectors in the vacuum sensor circuit, or a vacuum leak in the system.
3. How can I diagnose the Vacuum Sensor Circuit Fault associated with code C109E?
- Diagnosing involves checking the vacuum sensor, inspecting the wiring and connectors for damage, and conducting a vacuum leak test using a smoke machine.
4. Can a DIY enthusiast repair the Vacuum Sensor Circuit Fault related to code C109E?
- While some DIY enthusiasts may be able to replace the vacuum sensor or repair damaged wiring, diagnosing and fixing vacuum leaks may require professional help.
5. Is it safe to continue driving with OBDII code C109E active?
- It is not recommended to continue driving with this code active, as it can lead to further engine damage and potential safety risks due to decreased performance.
6. How much does it typically cost to repair the Vacuum Sensor Circuit Fault causing code C109E?
- 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.
7. Can a faulty vacuum sensor impact other vehicle systems beyond triggering code C109E?
- Yes, a faulty vacuum sensor can affect other systems like the EGR valve, fuel injection, and emission control, resulting in poor overall vehicle performance.
8. Will resetting the OBDII system clear code C109E, or is it necessary to fix the underlying issue?
- Resetting the system may temporarily clear the code, but it will likely reappear if the underlying Vacuum Sensor Circuit Fault is not addressed.
9. Are there any preventive measures to avoid encountering OBDII code C109E in the future?
- Regularly inspecting and maintaining the vacuum system, including the sensor and associated components, can help prevent the occurrence of code C109E.
10. Can a mechanic use a scan tool to pinpoint the exact location of the Vacuum Sensor Circuit Fault causing code C109E?
- Yes, a mechanic can use a scan tool to access live data and pinpoint the specific area of the vacuum sensor circuit that is causing the fault.
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