Quick Answer

P0686 means: DTC P0686 signifies a malfunction in the power relay circuit serving the ECM/PCM.

Fix: Check and replace faulty components Cost: $100 - $300 Time: 90-180 minutes

Can I drive with P0686? Immediate attention is recommended to prevent further engine issues.

Common Questions

What does P0686 mean and how does it affect my car?

DTC P0686 indicates a failure in the power relay circuit that feeds the ECM or PCM, potentially leading to engine performance issues including stalling, hesitation, and poor fuel efficiency. If ignored, it can result in significant engine and electronic component damage.

What are the most common causes of P0686 and how much does it cost to fix?

Common causes of P0686 include a faulty power relay, wiring issues, and a defective ECM. Repair costs can range from $100 for relay replacement to over $1,500 for ECM replacement, depending on the severity and required repairs.

Can I drive my car with P0686 or should I stop immediately?

It is not advisable to drive your vehicle if the P0686 code is present, as it can lead to engine stalling and unsafe driving conditions. Immediate inspection is recommended to prevent further damage.

How can I diagnose P0686 myself using GeekOBD APP?

Using the GeekOBD APP, connect to your vehicle’s OBD2 port. Run a complete scan to retrieve the P0686 code and any related codes. Analyze freeze frame data to understand the conditions under which the code was triggered, and check live data for voltage readings in the power circuit.

What vehicles are most commonly affected by P0686?

P0686 frequently appears in vehicles like the 2011-2018 Ford F-250, 2014-2017 Dodge Ram 1500, and several models from Chevrolet and GMC during the same years. Always check for any recalls or technical service bulletins related to the code.

How can I prevent P0686 from happening again?

Regular maintenance is key to preventing P0686. Ensure electrical connections are clean and secure, perform routine inspections of wiring, and keep the ECM updated with the latest software. Address any warning lights promptly to avoid further issues.

What is P0686?

DTC P0686 indicates a problem with the engine control module (ECM) or the powertrain control module (PCM) regarding the power relay circuit. Specifically, this code points to an issue with the power circuit that supplies voltage to the ECM or PCM. When this power relay circuit malfunctions, it can lead to the engine not starting or stalling, as the ECM/PCM doesn’t receive the necessary power to perform its functions. This can create a domino effect of problems, affecting fuel delivery, engine timing, and overall performance. Additionally, vehicle owners may notice decreased fuel efficiency, erratic engine behavior, or even a complete failure to start. It's crucial to address this issue promptly, as ignoring it may lead to further complications, including potential damage to the engine or other electronic components. If you're experiencing this code, it's advisable to consult a qualified technician who can conduct thorough diagnostics using tools like the GeekOBD APP to retrieve additional codes and freeze frame data, providing a clearer picture of the vehicle’s condition.

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

Symptoms

Common symptoms when P0686 is present:

  • Check engine light remains illuminated, indicating a fault within the engine management system.
  • Engine hesitates during acceleration, which can lead to a frustrating driving experience and potential safety hazards.
  • Fuel economy significantly decreased, often by 10-15%, leading to higher running costs and efficiency concerns.
  • Engine may stall unexpectedly, increasing the risk of accidents, especially in traffic.
  • Difficulty starting the vehicle, which can lead to being stranded or requiring roadside assistance.

Possible Causes

Most common causes of P0686 (ordered by frequency):

  1. Faulty power relay - This is the most common cause, occurring in about 40% of cases, where the relay fails to deliver power to the ECM/PCM.
  2. Wiring issues - Damaged or corroded wiring can disrupt the power supply, leading to this code being triggered. Regular inspections can prevent this.
  3. Faulty ECM/PCM - In some instances, the engine control module itself may be defective, though this is less common and should be confirmed with diagnostic tests.
  4. Poor ground connection - A bad ground can cause erratic behavior in the power circuit, leading to this code. Ensure all ground connections are clean and secure.
  5. Software issues - Rarely, outdated or corrupt software within the ECM/PCM can cause inconsistent power readings, leading to the P0686 code.

P0686 Repair Costs

Cost Breakdown by Repair Type

Power Relay Replacement

Replacing the faulty power relay that supplies power to the ECM/PCM.

  • Total: $100 - $300
  • Success rate: 85%
Wiring Repair

Repairing or replacing damaged wiring in the power circuit.

  • Total: $150 - $450
  • Success rate: 75%
ECM Replacement

Replacing a defective ECM/PCM if other diagnostics confirm this as the issue.

  • Total: $800 - $1,500
  • Success rate: 90%
Money-Saving Tips for P0686
  • 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 P0686 Diagnosis Process

Follow these systematic steps to accurately diagnose P0686. 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 multimeter or specific diagnostic tools to test suspected components like the power relay and wiring integrity (20-30 minutes)

Step 3: Component testing - Use multimeter or specific diagnostic tools to test suspected components like the power relay and wiring integrity (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 to see if the issue reoccurs (10-15 minutes)

Step 4: System function test - Verify proper operation after repairs and clear codes to see if the issue reoccurs (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 ensure no new codes appear (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and ensure no new codes appear (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: Power Relay Replacement on 2015 Ford F-250

Vehicle: 2015 Ford F-250, 85,000 miles

Problem: Customer reported intermittent stalling and check engine light.

Diagnosis: Using the GeekOBD APP, retrieved P0686 code alongside other related codes. Visual inspection revealed a burnt power relay.

Solution: Replaced the power relay and cleared the codes. Conducted a road test.

Cost: $150 (diagnostic fee plus parts)

Result: Customer reported no further issues, and the vehicle has been running smoothly since.

Case Study 2: Wiring Repair on 2014 Dodge Ram 1500

Vehicle: 2014 Dodge Ram 1500, 70,000 miles

Problem: Vehicle had difficulty starting and check engine light was on.

Diagnosis: P0686 code confirmed. Visual inspection revealed corroded wiring in the relay circuit.

Solution: Repaired all damaged wiring and replaced connectors as necessary.

Cost: $250 (including parts and labor)

Result: Vehicle started without issues post-repair, and the customer has not reported any further problems.

Diagnose P0686

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis

Code Information

Code: P0686
System: Powertrain (Engine, Transmission, Emissions)
Severity: HIGH
Category: Engine Codes