Introduction:
The P0086 diagnostic trouble code (DTC) indicates a problem with the exhaust valve control solenoid circuit on bank 2 of your engine. This code signals that the engine control unit (ECU) has detected an abnormally high voltage reading in the control circuit for the exhaust valve solenoid, which is crucial for variable valve timing (VVT) functionality. Understanding the causes, symptoms, and troubleshooting steps for P0086 is essential for maintaining optimal engine performance and fuel efficiency.
Comprehensive Table: P0086 Exhaust Valve Control Solenoid Circuit High (Bank 2)
| Category | Description | Possible Causes |
|---|---|---|
| Basic Information | Definition: Exhaust Valve Control Solenoid Circuit High (Bank 2) indicates the voltage in the control circuit for the exhaust valve solenoid on engine bank 2 is higher than expected. Bank 2 refers to the side of the engine that does not contain cylinder #1. | Open circuit in the exhaust valve control solenoid circuit; Short circuit to voltage in the exhaust valve control solenoid circuit; Faulty exhaust valve control solenoid; Faulty ECU; Wiring harness damage or corrosion; Poor electrical connections; Low engine oil level/pressure; Incorrect engine oil viscosity. |
| Symptoms | Common symptoms include: Check Engine Light (CEL) illuminated; Poor engine performance; Reduced fuel economy; Rough idling; Stalling; Misfires; Increased emissions; VVT system malfunction. | Severity varies. Performance issues range from subtle to severe. Ignoring the code can lead to further engine damage. |
| Diagnostic Steps | Recommended steps: Visual inspection of wiring and connectors; Measuring resistance of the exhaust valve control solenoid; Checking voltage at the solenoid connector; Testing the solenoid with a scan tool; Inspecting engine oil level and pressure; Inspecting camshaft position sensor/CKP sensor data. | Use a multimeter, OBD-II scanner, and wiring diagrams. Follow the manufacturer's diagnostic procedures. Proper tools are essential for accurate diagnosis. |
| Potential Solutions | Possible solutions include: Repairing or replacing damaged wiring; Repairing or replacing corroded connectors; Replacing the exhaust valve control solenoid; Replacing the ECU (rare); Flushing or changing engine oil; Addressing low oil pressure issues. | Prioritize the most likely causes. Start with simple repairs (wiring, connectors) before replacing components. Confirm the repair fixed the issue by clearing the code and monitoring engine performance. |
| Variable Valve Timing (VVT) | Explanation of VVT: VVT systems optimize engine performance by adjusting the timing of the intake and exhaust valves. This allows the engine to adapt to different driving conditions, improving power, fuel economy, and emissions. The exhaust valve control solenoid controls the oil flow to the exhaust cam phaser, which adjusts the exhaust valve timing. | Malfunctioning VVT leads to inefficient combustion and reduced engine performance. The ECU relies on the VVT system to maintain optimal engine operation. |
| Bank 2 Identification | Determining Bank 2: On V-type engines (V6, V8, V10), Bank 1 is typically the bank containing cylinder #1. Bank 2 is the opposite bank. On inline engines, there is only one bank. The code usually indicates a wiring or solenoid issue, and is less common on inline engines. Always consult the vehicle's service manual for the correct bank identification. | Incorrectly identifying the bank can lead to wasted time and incorrect repairs. Refer to the vehicle's service manual for the correct bank identification. |
| Exhaust Valve Control Solenoid Function | The exhaust valve control solenoid is an electro-hydraulic valve that regulates oil pressure to the exhaust cam phaser. The ECU controls the solenoid by varying the voltage applied to it. The solenoid's position determines the amount of oil flowing to the phaser, which in turn adjusts the exhaust valve timing. A "circuit high" fault indicates the ECU is seeing a higher voltage than expected. | A faulty solenoid can cause incorrect exhaust valve timing, leading to poor engine performance. The solenoid should operate smoothly and respond correctly to changes in voltage. |
| Related Codes | Common related codes: P0010, P0011, P0012, P0020, P0021, P0022, P0087, P0088, P0089. These codes often relate to other VVT components or issues with the engine oil system. | Related codes can provide clues about the underlying cause of the P0086 code. Diagnosing related codes can help narrow down the possible causes. |
| Engine Oil's Role | Engine oil is crucial for VVT system operation. It provides the hydraulic pressure needed to actuate the cam phasers. Low oil level, low oil pressure, or incorrect oil viscosity can all affect the VVT system's performance. Old or contaminated oil can also clog the solenoid and phaser, leading to malfunctions. | Regular oil changes with the correct viscosity oil are essential for maintaining the VVT system. Low oil level or pressure should be addressed immediately to prevent engine damage. |
| Wiring and Connectors | The wiring and connectors in the exhaust valve control solenoid circuit are susceptible to damage from heat, vibration, and exposure to the elements. Corrosion, loose connections, and damaged wires can all cause electrical problems that trigger the P0086 code. Thorough inspection of the wiring and connectors is crucial. | Carefully inspect the wiring harness for any signs of damage, such as frayed wires or melted insulation. Clean corroded connectors with electrical contact cleaner. Ensure that all connections are secure. |
| ECU Failure | While less common, a faulty ECU can sometimes cause the P0086 code. The ECU controls the exhaust valve control solenoid, and if the ECU is malfunctioning, it may send incorrect signals or fail to properly monitor the circuit. ECU failure is usually diagnosed after ruling out other possible causes. | Replacing the ECU should be considered as a last resort. Before replacing the ECU, make sure to thoroughly test all other components in the system. Consult with a qualified technician for ECU diagnostics. |
| Scan Tool Data | A scan tool can be used to monitor the exhaust valve control solenoid's operation. The scan tool can display the solenoid's duty cycle, voltage, and current. This data can help to determine if the solenoid is functioning properly and if the ECU is sending the correct signals. Comparing the data to the manufacturer's specifications can aid in diagnosis. | Understanding how to interpret scan tool data is crucial for diagnosing VVT system problems. Consult the vehicle's service manual for the correct specifications. |
Detailed Explanations:
Basic Information: The P0086 code indicates a high voltage reading in the exhaust valve control solenoid circuit on bank 2. This means the ECU is detecting more voltage than expected, suggesting a potential short to voltage or an open circuit further down the line. Bank 2 is the engine bank opposite cylinder #1.
Symptoms: The most common symptom is the illuminated check engine light (CEL). Other symptoms include reduced engine performance, poor fuel economy, rough idling, stalling, misfires, and increased emissions. These symptoms arise because the VVT system is not functioning correctly.
Diagnostic Steps: Begin with a visual inspection of the wiring and connectors associated with the solenoid. Next, measure the resistance of the solenoid itself to check for internal shorts or opens. Use a scan tool to monitor the solenoid's operation and compare the readings to the manufacturer's specifications. Also, check engine oil level and pressure.
Potential Solutions: The solutions range from simple fixes like repairing damaged wiring or corroded connectors to more complex repairs like replacing the solenoid or, in rare cases, the ECU. Addressing low oil pressure or incorrect oil viscosity can also resolve the issue.
Variable Valve Timing (VVT): VVT systems optimize engine performance by adjusting the timing of the intake and exhaust valves. This allows the engine to adapt to different driving conditions, improving power, fuel economy, and emissions. The exhaust valve control solenoid is a critical part of this system.
Bank 2 Identification: On V-type engines, Bank 1 is typically the bank containing cylinder #1. Bank 2 is the opposite bank. Always consult the vehicle's service manual for the correct bank identification, as it can vary between manufacturers.
Exhaust Valve Control Solenoid Function: The exhaust valve control solenoid regulates oil pressure to the exhaust cam phaser, controlling exhaust valve timing. The ECU controls the solenoid by varying the voltage applied to it. A "circuit high" fault indicates the ECU is seeing a higher voltage than expected in this control circuit.
Related Codes: The presence of other codes, such as P0010, P0011, P0012, P0020, P0021, and P0022, can provide valuable clues about the root cause of the P0086 code. These codes often relate to other VVT components or issues with the engine oil system.
Engine Oil's Role: Engine oil is essential for the proper functioning of the VVT system. It provides the hydraulic pressure needed to actuate the cam phasers. Low oil level, low oil pressure, or incorrect oil viscosity can all negatively affect the VVT system's performance.
Wiring and Connectors: The wiring and connectors in the exhaust valve control solenoid circuit are prone to damage from heat, vibration, and environmental factors. Corrosion, loose connections, and damaged wires can all cause electrical problems that trigger the P0086 code.
ECU Failure: While rare, a faulty ECU can sometimes cause the P0086 code. The ECU controls the exhaust valve control solenoid, and a malfunctioning ECU may send incorrect signals or fail to properly monitor the circuit. ECU replacement is typically a last resort.
Scan Tool Data: Using a scan tool to monitor the solenoid's operation is a crucial diagnostic step. The scan tool can display the solenoid's duty cycle, voltage, and current, helping to determine if the solenoid is functioning properly and if the ECU is sending the correct signals.
Frequently Asked Questions:
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What does the P0086 code mean? It means the ECU has detected an abnormally high voltage in the exhaust valve control solenoid circuit on bank 2.
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Can I drive with a P0086 code? It's not recommended, as it can lead to reduced engine performance and potentially further engine damage. Get it checked as soon as possible.
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How do I fix a P0086 code? The fix depends on the cause, but common solutions include repairing wiring, replacing the solenoid, or addressing oil pressure issues.
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What is Bank 2? On a V-type engine, Bank 2 is the side of the engine that does not contain cylinder #1.
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Is the exhaust valve control solenoid expensive to replace? The cost varies depending on the vehicle make and model, but it's generally a moderately priced part. Labor costs can also vary.
Conclusion:
The P0086 code indicates a high voltage issue in the exhaust valve control solenoid circuit on bank 2, often impacting engine performance and fuel efficiency. Thorough diagnosis and repair are essential to restore proper VVT system functionality and prevent further engine damage.