AutoCodes – Generic – P109C

P109C Code - Open in Fuel Pressure Switching Valve Circuit

Quick Answer

A Flexible Fuel Vehicle (FFV) can be used with a fuel containing a high concentration of ethyl alcohol. Common causes include Faulty Fuel Pressure Switching Valve, Fuel Pressure Switching Valve harness is open or shorted, Fuel Pressure Switching Valve circuit poor electrical connection. 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: P109C indicates Open in Fuel Pressure Switching Valve Circuit.
Common causes: Common causes include Faulty Fuel Pressure Switching Valve, Fuel Pressure Switching Valve harness is open or shorted, Fuel Pressure Switching Valve circuit poor electrical connection.
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 5,002

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 Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P109C Description

A Flexible Fuel Vehicle (FFV) can be used with a fuel containing a high concentration of ethyl alcohol.
This FFV uses a fuel pressure switching system which changes the fuel pressure to low or high using a fuel pressure switching valve.
The code is stored when a malfunction is detected in the fuel pressure switching valve circuit. If the voltage of the fuel pressure switching valve circuit is different from the voltage commanded by the Engine Control Module (ECM), the ECM determines that the fuel pressure switching valve circuit is open or shorted, and stores a DTC.

OBDII Code P109C - Open in Fuel Pressure Switching Valve Circuit - AutoCodes.com — P109C Code - Open in Fuel Pressure Switching Valve Circuit

What does this mean?

What are the Possible Causes of the DTC P109C?

Faulty Fuel Pressure Switching Valve
Fuel Pressure Switching Valve harness is open or shorted
Fuel Pressure Switching Valve circuit poor electrical connection
Faulty F/PMP VSV relay
Faulty Engine Control Module (ECM)

How to Fix the DTC P109C?

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 P109C 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.

Need more information about the P109C code?

Need more information on how to fix the P109C code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P109C code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P109C Lexus — Open in Fuel Pressure Switching Valve Circuit
P109C Toyota — Open in Fuel Pressure Switching Valve Circuit

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 P109C Code

1. What are the common symptoms of OBDII code P109C?

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

2. What are the typical causes of OBDII code P109C?

- The code is often triggered by a faulty fuel pressure switching valve, wiring issues, or a malfunctioning fuel pump.

3. How can I diagnose the Open in Fuel Pressure Switching Valve Circuit issue?

- Use a scan tool to read the code and perform a visual inspection of the fuel pressure switching valve and related wiring for any visible damage.

4. Can a bad fuel pressure switching valve be repaired, or does it need to be replaced?

- In most cases, a faulty fuel pressure switching valve will need to be replaced to resolve the P109C code.

5. Are there any specific repair tips for fixing the Open in Fuel Pressure Switching Valve Circuit?

- Ensure all connections are secure, check for any corrosion or damage to the wiring, and consider consulting a professional for proper diagnosis and repair.

6. Is it safe to continue driving with OBDII code P109C present?

- It is not recommended to drive with the code active, as it can lead to further engine damage and potential safety hazards.

7. How much does it typically cost to repair the Open in Fuel Pressure Switching Valve Circuit issue?

- The cost of repair can vary depending on the extent of the damage and whether you choose to do the repair yourself or take it to a mechanic.

8. Can OBDII code P109C be triggered by other underlying issues?

- While the code is primarily related to the fuel pressure switching valve circuit, it's essential to ensure there are no other fuel system or wiring issues causing the problem.

9. Will resetting the OBDII code P109C make it go away permanently?

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

10. How can I prevent OBDII code P109C from occurring in the future?

- Regular maintenance checks, including inspecting the fuel system components and wiring, can help prevent the recurrence of the Open in Fuel Pressure Switching Valve Circuit issue.