P0691 - Engine Cooling Fan Control Circuit Range/Performance Problem in Popular Makes like Ford and Chevrolet

Quick Answer

P0691 means: DTC P0691 indicates an issue with the engine cooling fan control circuit, affecting engine temperature regulation.

Fix: Check and replace faulty components Cost: $80 - $150 Time: 90-180 minutes

Can I drive with P0691? Address immediately to prevent engine overheating and potential damage.

Common Questions

What does P0691 mean and how does it affect my car?

DTC P0691 indicates a problem with the cooling fan control circuit, which is vital for keeping your engine cool. If this issue is not resolved, your engine may overheat, leading to severe damage over time. It's important to address this code promptly to maintain vehicle integrity and performance.

What are the most common causes of P0691 and how much does it cost to fix?

The most common cause of DTC P0691 is a faulty cooling fan relay, accounting for about 60% of cases. Repair costs for this issue typically range from $80 to $150. Other causes include wiring issues (costing $100 to $300) and a failed cooling fan motor (costing $200 to $400).

Can I drive my car with P0691 or should I stop immediately?

You should avoid driving your vehicle if you see the P0691 code, as it indicates potential overheating risks. Continuing to drive could lead to severe engine damage, so it's best to have the issue diagnosed and repaired as soon as possible.

How can I diagnose P0691 myself using GeekOBD APP?

Using the GeekOBD APP, you can perform a self-diagnosis by connecting the app to your vehicle's OBD2 port. Start by scanning for codes, then review the freeze frame data to see if any conditions, like temperature or speed, triggered the P0691 code. This information will help you pinpoint the issue.

What vehicles are most commonly affected by P0691?

DTC P0691 is commonly seen in vehicles such as the 2013-2018 Ford F-150 and the 2014-2019 Chevrolet Silverado. If you own any of these models, it's wise to be aware of this code and its implications.

How can I prevent P0691 from happening again?

To prevent P0691 from recurring, regularly inspect your vehicle's cooling system, including the fan, relay, and wiring. Make sure to address any signs of wear, such as frayed wires or weak connections. A routine maintenance schedule that includes coolant checks and periodic inspections can help catch issues before they escalate.

What is P0691?

The diagnostic trouble code (DTC) P0691 indicates a malfunction in the engine cooling fan control circuit. Specifically, this code is triggered when the Engine Control Module (ECM) detects that the cooling fan is not operating within its expected range or performance parameters. This can lead to overheating issues if the cooling system fails to dissipate heat effectively. Commonly, this problem arises in vehicles like the 2013-2018 Ford F-150 and 2014-2019 Chevrolet Silverado, where the cooling fan is essential for maintaining optimal engine temperature. When the fan fails to engage or disengage appropriately, it can cause the engine to run hotter than normal, which can lead to severe engine damage if not addressed promptly. Drivers may notice that their engine temperature gauge is reading higher than usual or that the check engine light has illuminated. Ignoring this code can result in costly repairs down the line, so it's crucial to diagnose and correct the issue as soon as possible to ensure your vehicle operates efficiently and safely.

System: P - Powertrain (Engine, Transmission, Emissions)

Symptoms

Common symptoms when P0691 is present:

  • Check engine light stays on constantly, indicating an issue with the cooling system.
  • Engine temperature gauge displays higher-than-normal readings, suggesting overheating risks.
  • Engine hesitates during acceleration, which may happen due to overheating.
  • Unusual noises from the engine compartment, potentially caused by a malfunctioning cooling fan.
  • Fuel economy decreased by 10-15%, as the engine may be working harder to compensate for overheating.

Possible Causes

Most common causes of P0691 (ordered by frequency):

  1. Faulty cooling fan relay (60% likelihood) - A damaged relay can prevent the fan from receiving the signal to turn on, leading to overheating.
  2. Wiring issues (25% likelihood) - Damaged, frayed, or corroded wiring in the cooling fan circuit can interrupt power and affect fan operation.
  3. Malfunctioning ECM (10% likelihood) - A failure in the engine control module can result in incorrect signals being sent to the cooling fan.
  4. Less common cause: Failed cooling fan motor - If the motor itself is defective, it will not operate even if signals are correctly sent.
  5. Rare but possible cause: Faulty temperature sensor - This can provide incorrect data to the ECM, resulting in inappropriate fan operation.

P0691 Repair Costs

Cost Breakdown by Repair Type

Cooling Fan Relay Replacement

Replacing a faulty cooling fan relay to restore proper function.

  • Total: $80 - $150
  • Success rate: 85%
Wiring Repair

Repairing or replacing damaged wiring in the cooling fan circuit.

  • Total: $100 - $300
  • Success rate: 75%
Cooling Fan Motor Replacement

Replacing the cooling fan motor if it has failed.

  • Total: $200 - $400
  • Success rate: 90%
Money-Saving Tips for P0691
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional P0691 Diagnosis Process

Follow these systematic steps to accurately diagnose P0691. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Component testing - Use a multimeter or specific diagnostic tools to test the cooling fan relay and wiring (20-30 minutes)

Step 3: Component testing - Use a multimeter or specific diagnostic tools to test the cooling fan relay and wiring (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: System function test - Verify proper operation after repairs and clear codes (10-15 minutes)

Step 4: System function test - Verify proper operation after repairs and clear codes (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and monitor temperature (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and monitor temperature (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: Cooling Fan Relay Replacement on 2015 Ford F-150

Vehicle: 2015 Ford F-150, 75,000 miles

Problem: Customer reported the check engine light was on and the engine was overheating.

Diagnosis: After running a diagnostic scan using GeekOBD APP, code P0691 was retrieved. A visual inspection showed the cooling fan relay was burnt out.

Solution: Replaced the faulty cooling fan relay with a new part. Conducted a system function test to ensure the fan was operating correctly.

Cost: $120 (including parts and labor)

Result: The check engine light was cleared, and the vehicle returned to normal operating temperature.

Case Study 2: Wiring Repair on 2014 Chevrolet Silverado

Vehicle: 2014 Chevrolet Silverado, 85,000 miles

Problem: Customer experienced intermittent overheating and a check engine light.

Diagnosis: Diagnostic scan revealed code P0691. Further testing showed damaged wiring in the cooling fan circuit.

Solution: Repaired the damaged wiring and verified the cooling system operation. Cleared the code.

Cost: $220 (specific cost breakdown for parts and labor included)

Result: The vehicle's cooling system function returned to normal, and the customer reported no further issues.

Diagnose P0691

Use GeekOBD APP for professional diagnosis!

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  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: P0691
System: Powertrain (Engine, Transmission, Emissions)
Severity: HIGH
Category: Engine Codes