Quick Answer
P0685 means: P0685 indicates an issue with the PCM relay control circuit, affecting engine performance.
Can I drive with P0685? Immediate attention is required to prevent further engine complications.
Common Questions
What does P0685 mean and how does it affect my car?
The P0685 code points to an issue with the Powertrain Control Module relay control circuit. This can lead to various engine performance issues, such as stalling, lack of power, or even starting problems. If not addressed, it can cause further complications, making your car less reliable. It's crucial to diagnose and fix this issue promptly.
What are the most common causes of P0685 and how much does it cost to fix?
Common causes include a faulty PCM relay, damaged wiring, and in some cases, a malfunctioning PCM itself. Repair costs can range from $50 to $800 depending on whether you need a simple relay replacement or a full PCM replacement.
Can I drive my car with P0685 or should I stop immediately?
While you may still be able to drive your car, it is not advisable. Ignoring the P0685 code can lead to stalling or reduced performance, which could create dangerous driving conditions. It’s best to address this issue as soon as possible.
How can I diagnose P0685 myself using GeekOBD APP?
Using the GeekOBD APP, you can perform an OBD2 scan to retrieve the P0685 code and any other related codes. Look at the freeze frame data to see the conditions when the code was triggered. This helps you understand the context of the problem. You can also use the app to clear the codes after repairs to see if they reappear.
What vehicles are most commonly affected by P0685?
Commonly affected vehicles include the 2005-2015 Ford F-Series, Dodge Ram, and Chrysler 300. If you own one of these models, be aware of this code and its potential implications.
How can I prevent P0685 from happening again?
Regular maintenance, including checking wiring and electrical connections for wear, can help prevent future issues. Additionally, using quality parts during repairs will reduce the risk of recurrence.
What is P0685?
The DTC code P0685 indicates a problem with the Powertrain Control Module (PCM) relay control circuit. This issue can arise due to various reasons, including electrical faults, damaged wiring, or malfunctioning components. Essentially, the PCM relies on a properly functioning relay to receive power and operate effectively. If this relay is not working as intended, it can lead to a range of problems, including engine stalling, reduced power, or failure to start. Drivers may notice the check engine light illuminating on their dashboard, signaling a fault that requires immediate attention. For vehicle owners, understanding this code is crucial, as it can significantly impact vehicle performance and reliability. Common vehicles affected by this code include models from Ford, Chrysler, and Dodge, particularly those manufactured between 2005 and 2015. Ignoring this code can lead to more severe engine issues, increased repair costs, and unsafe driving conditions. It’s essential to address the P0685 code promptly to ensure your vehicle continues to operate smoothly and efficiently.
System: P - Powertrain (Engine, Transmission, Emissions)
Symptoms
Common symptoms when P0685 is present:
- Check engine light stays on constantly, signaling a persistent problem with the PCM.
- Engine hesitates during acceleration, causing a lack of power when you need it most.
- Fuel economy decreased by 10-15%, resulting in more frequent trips to the gas station.
- Vehicle may stall unexpectedly, which can be dangerous in traffic.
- Difficulties with starting the car, especially on colder mornings or after extended periods of inactivity.
Possible Causes
Most common causes of P0685 (ordered by frequency):
- Faulty PCM relay (60% likelihood) – The relay may be worn out or damaged, preventing proper power supply.
- Damaged wiring or connections (25% likelihood) – Corrosion or breaks in the wiring can disrupt the power flow to the PCM.
- Malfunctioning PCM (10% likelihood) – In some cases, the PCM itself may have internal issues requiring replacement.
- Electrical shorts or grounding issues (4% likelihood) – Poor grounding can lead to erratic behavior of the PCM relay.
- Fuse issues (1% likelihood) – A blown fuse related to the PCM circuit may also trigger this trouble code.
P0685 Repair Costs
Cost Breakdown by Repair Type
PCM Relay Replacement
Replacing faulty PCM relay with a new OEM part.
- Total: $50 - $150
- Success rate: 90%
Wiring Repair
Repairing or replacing damaged wiring and connectors in the PCM circuit.
- Total: $100 - $300
- Success rate: 85%
PCM Replacement
Replacing the PCM if it is found to be defective after thorough testing.
- Total: $300 - $800
- Success rate: 95%
Money-Saving Tips for P0685
- 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 P0685 Diagnosis Process
Follow these systematic steps to accurately diagnose P0685. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)
Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)
Step 3: Component testing - Use a multimeter or specific diagnostic tools to test the PCM relay and wiring (20-30 minutes)
Step 4: System function test - Verify proper operation after repairs and clear codes using the GeekOBD APP (10-15 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success (15-20 minutes)
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: Ford F-150 Power Problem
Vehicle: 2010 Ford F-150, 80,000 miles
Problem: Customer reported intermittent stalling and check engine light.
Diagnosis: Scanned for codes and found P0685 along with related codes. Inspected the PCM relay and wiring.
Solution: Replaced the faulty PCM relay and repaired corroded wiring.
Cost: $150 (relay and labor)
Result: Customer reported improved engine performance and no further issues.
Case Study 2: Chrysler 300 Starting Issues
Vehicle: 2008 Chrysler 300, 95,000 miles
Problem: Customer experienced starting difficulties and check engine light.
Diagnosis: Diagnostic scan revealed P0685. Tested PCM and relay functionality.
Solution: Replaced the PCM after confirming the relay was functioning correctly.
Cost: $750 (PCM replacement)
Result: Vehicle started reliably after repair, and the customer was satisfied.