AutoCodes – Ford – P0691 Ford

P0691 Ford Code - Cooling Fan 1 Control Circuit Low

Quick Answer

The Engine Control Module (ECM) grounds the low-speed relay, which is the Fan Low relay, and the high-speed relay, which is the Fan High relay, control circuits through an internal solid-state device called a driver. Common causes include Faulty Cooling Fan 1 Relay, Cooling Fan 1 Relay harness is open or shorted, Cooling Fan 1 Relay 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: P0691 Ford indicates Cooling Fan 1 Control Circuit Low.
Common causes: Common causes include Faulty Cooling Fan 1 Relay, Cooling Fan 1 Relay harness is open or shorted, Cooling Fan 1 Relay 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 4,993

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 Jan 11, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0691 Ford Description

The Engine Control Module (ECM) grounds the low-speed relay, which is the Fan Low relay, and the high-speed relay, which is the Fan High relay, control circuits through an internal solid-state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line that is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the ECM detects that the actual state of the control circuit does not match the expected state, a Diagnostic Trouble Code (DTC) will set.

OBDII Code P0691 Ford - Cooling Fan 1 Control Circuit Low - AutoCodes.com — P0691 Ford Code - Cooling Fan 1 Control Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0691 Ford?

Faulty Cooling Fan 1 Relay
Cooling Fan 1 Relay harness is open or shorted
Cooling Fan 1 Relay circuit poor electrical connection
Faulty Cooling Fan 1
Faulty Engine Control Module (ECM)

How to Fix the DTC P0691 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 P0691 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 P0691 Ford Code

1. What are the common symptoms of OBDII code P0691 (Cooling Fan 1 Control Circuit Low) in a Ford vehicle?

- Common symptoms include overheating of the engine, the cooling fan not turning on or running at a lower speed than normal, and a potential increase in the vehicle's temperature gauge reading.

2. What are the possible causes of OBDII code P0691 in a Ford, indicating a Cooling Fan 1 Control Circuit Low issue?

- The code P0691 in a Ford can be caused by a faulty cooling fan motor, a malfunctioning cooling fan relay, damaged wiring or connectors in the cooling fan circuit, or a defective engine control module (ECM).

3. How can I diagnose the Cooling Fan 1 Control Circuit Low issue related to OBDII code P0691 in my Ford?

- A diagnostic scan tool can help identify the specific cause by pinpointing the exact component or circuit that is malfunctioning. Additionally, visually inspecting the wiring and connectors for any visible damage is recommended.

4. What are some repair tips for resolving OBDII code P0691 in a Ford related to the Cooling Fan 1 Control Circuit Low problem?

- Start by checking the cooling fan fuse, relay, and wiring connections for any issues. If these components are in good condition, then testing the cooling fan motor and the ECM may be necessary to determine the root cause.

5. Can driving with OBDII code P0691 (Cooling Fan 1 Control Circuit Low) in a Ford cause further damage to the vehicle?

- Continuing to drive with the cooling fan malfunctioning can lead to engine overheating, potential damage to engine components, and increased risk of engine failure. It is advisable to address the issue promptly.

6. Is it possible to reset the OBDII code P0691 in a Ford to see if the issue resolves itself?

- While clearing the code may temporarily turn off the check engine light, it will not fix the underlying problem causing the Cooling Fan 1 Control Circuit Low issue. It is recommended to diagnose and repair the root cause of the code.

7. How much does it typically cost to repair OBDII code P0691 in a Ford related to the Cooling Fan 1 Control Circuit Low problem?

- The cost of repair can vary depending on the specific cause of the issue. Costs may include replacement of the cooling fan motor, relay, wiring repairs, or ECM replacement. It is best to consult a professional for an accurate estimate.

8. Are there any preventative measures to avoid encountering OBDII code P0691 (Cooling Fan 1 Control Circuit Low) in a Ford in the future?

- Regularly inspecting the cooling system components, including the fan, relay, and wiring, can help prevent issues that may trigger the code P0691. Keeping the cooling system well-maintained can reduce the risk of encountering this problem.