P1655 - EVAP Purge Solenoid Control Circuit

Introduction:

The P1655 diagnostic trouble code (DTC) indicates a problem within the Evaporative Emission (EVAP) control system, specifically related to the purge solenoid control circuit. This code signifies that the Engine Control Module (ECM) has detected an anomaly in the electrical circuit controlling the EVAP purge solenoid, which plays a crucial role in managing fuel vapor emissions. Addressing this code promptly is important to ensure optimal engine performance, fuel efficiency, and compliance with emissions regulations.

Understanding the P1655 Code: A Comprehensive Guide

Detailed Explanations

Code & Name: P1655 - EVAP Purge Solenoid Control Circuit This is the specific diagnostic trouble code (DTC) that your vehicle's computer has registered. It directly points to an issue within the electrical circuit that controls the EVAP purge solenoid.

System: Evaporative Emission (EVAP) Control System The EVAP system is designed to prevent fuel vapors from escaping into the atmosphere. It captures these vapors and stores them until the engine can safely burn them, reducing emissions.

Component: EVAP Purge Solenoid The EVAP purge solenoid is an electrically controlled valve that regulates the flow of fuel vapors from the EVAP canister into the engine's intake manifold. It's a critical component for managing fuel vapor recycling.

Circuit: Control Circuit of the EVAP Purge Solenoid This refers to the electrical wiring, connectors, and the ECM's internal circuitry that are responsible for operating the EVAP purge solenoid. The ECM sends a signal to the solenoid to open or close, controlling the flow of fuel vapors.

Severity: Moderate to High While the P1655 code may not always cause immediate and severe drivability problems, it should be addressed promptly. A malfunctioning EVAP system can lead to increased emissions, reduced fuel economy, and potential engine performance issues. Ignoring it could also lead to failing an emissions test.

Symptoms:

• Check Engine Light: This is the most obvious symptom, indicating that the ECM has detected a problem.
• Possible Fuel Odor: If the EVAP system is not functioning correctly, fuel vapors may escape, resulting in a noticeable fuel odor, especially near the fuel tank or engine compartment.
• Reduced Fuel Economy: A faulty EVAP system can affect the air/fuel mixture, leading to decreased fuel efficiency.
• Possible Engine Performance Issues: In some cases, a malfunctioning EVAP system can cause rough idling, hesitation during acceleration, or even stalling.

Possible Causes:

• Faulty Purge Solenoid: The solenoid itself may be defective, either electrically or mechanically. The valve may be stuck open or closed, or the solenoid coil may be open or shorted.
• Wiring Issues (Shorts, Opens, Corrosion): Damaged wiring can disrupt the electrical signal to the solenoid. This includes frayed wires, broken connections, or corrosion within the wiring harness.
• Connector Problems: Loose, corroded, or damaged connectors can prevent proper electrical contact, leading to a malfunction.
• ECM Issues: Although less common, a faulty ECM can sometimes be the cause of the P1655 code. The ECM may not be sending the correct signal to the solenoid.
• Blocked or Leaking EVAP Hoses/Lines: While not directly related to the control circuit, a blockage or leak in the EVAP system can indirectly trigger the code.
• Faulty Fuel Tank Pressure Sensor: Although not directly related to the solenoid circuit, an inaccurate reading from the fuel tank pressure sensor can affect the EVAP system's operation and potentially trigger the P1655 code.

Diagnostic Steps:

1. Visual Inspection: Begin by visually inspecting the purge solenoid, wiring, and connectors for any obvious signs of damage, such as frayed wires, corroded terminals, or cracked hoses.
2. Scan Tool Diagnostics: Use a scan tool to read the DTCs stored in the ECM. This will confirm the P1655 code and may provide additional information. Monitor the purge solenoid's operation using the scan tool's data stream.
3. Circuit Testing (Voltage, Resistance, Continuity): Use a multimeter to test the voltage, resistance, and continuity of the purge solenoid control circuit. This will help identify any shorts, opens, or high resistance connections.
4. Component Testing (Solenoid Activation): Use a scan tool or a direct power source to activate the purge solenoid. Listen for a clicking sound, which indicates that the solenoid is functioning. Also, check for proper airflow through the solenoid when activated.
5. Smoke Testing (EVAP Leaks): Perform a smoke test to check for leaks in the EVAP system. This involves introducing smoke into the system and observing where it escapes.

Common Repair Solutions:

• Replacing the Purge Solenoid: If the purge solenoid is found to be faulty, replacing it is the most common solution.
• Repairing or Replacing Damaged Wiring/Connectors: Repair any damaged wiring or connectors in the purge solenoid control circuit. This may involve splicing wires, replacing connectors, or repairing corroded terminals.
• Clearing Blockages in EVAP Hoses/Lines: Remove any blockages in the EVAP hoses or lines. This may involve using compressed air or a vacuum to clear the lines.
• Replacing Fuel Tank Pressure Sensor: If the fuel tank pressure sensor is found to be faulty, replacing it may be necessary.
• ECM Replacement (Rare): ECM replacement is rarely necessary, but it may be required if the ECM is found to be the cause of the P1655 code. This should only be considered after all other possible causes have been ruled out.

Frequently Asked Questions

• What does the P1655 code mean? The P1655 code indicates a problem with the electrical circuit controlling the EVAP purge solenoid. This means the engine computer isn't properly controlling the flow of fuel vapors to be burned.

• Can I drive with a P1655 code? While you can drive with this code, it's not recommended for extended periods. It can lead to reduced fuel economy and increased emissions, and potentially cause engine performance issues.

• How serious is the P1655 code? The seriousness is moderate to high, indicating that there is an issue that needs to be addressed. While it may not immediately cause severe damage, ignoring it can lead to further complications.

• Will replacing the purge solenoid always fix the P1655 code? Not always. Replacing the solenoid is a common fix, but the problem could also be related to wiring, connectors, or the ECM. Thorough diagnostics are crucial.

• **Can a loose gas cap cause the