P0085 OBD Error Code: Problem & Solutions

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If you experience rough engine idles, reduced performance and lowered fuel economy, this can be due to Variable Valve Timing (VVT) failure and even the vehicle going into failsafe mode to avoid engine from further damages. All these problems can be an indication towards OBD code P0085 error being stored in the Powertrain Control Module (PCM).

OBD-II Code Decreased engine performance is defined as a Exhaust Valve Control Solenoid Circuit Low.

This trouble code only applies to vehicles that are 1996 or newer with VVT (Variable Valve Timing). This code will trigger when there is a problem with the VVT (Variable Valve Timing) control solenoid electrical circuit. Bank 2 is the side of the engine with cylinder 2 and if the engine is inline then there only is 1 bank. The control solenoid controls camshaft position with oil pressure, and the control solenoid is managed by the PCM (Powertrain Control Module) through voltage signals.

When the Check Engine Light is set the ECM puts the vehicle into a failsafe mode, this disables the variable valve timing.

What causes the problem of Exhaust Valve Control Solenoid Circuit Low (Bank 2)?

• Improper functioning of ECM
• Wiring harness is open/short/corroded/damaged
• Faulty electrical connections
• Bank 2 exhaust valve control solenoid faulty

1. Engine Control Module - ECM, if faulty will interpret the information wrongly and will affect the overall engine’s performance directly. Thus, replace faulty components now!
2. Variable Valve Timing - VVT is responsible to take part in engine performance and emissions. So, the faulty VVT should be repaired/replaced at first instance.
3. Exhaust Valve - Exhaust valve affects the internal combustion process and thus faulty valves should be repaired immediately. Replace them now!
4. Diagnostic Tools - Use professional grade diagnostic tools to solve any OBD code error. Buy quality diagnostic and scan tools from us.
5. Engine Control Unit - ECU can be at fault and hamper the engine performance and fuel delivery and transmission system. Replace faulty components now!

Engine Control Module (ECM) detects the low voltage in the bank 2 control solenoid and this causes a Check Engine Light to be illuminated on the dashboard. Following are the most common indications of OBD code P0085

Common Symptoms

• Reduced acceleration
• Reduced engine power
• Affected fuel economy
• Check Engine Light On
• Increased emissions

• Replacement of the ECM
• Replacement of the harness wiring
• Replacement of bank 2 exhaust valve control solenoid
• Fixing damaged or poor electrical connection 

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Since this DTC notifies a circuit problem, the technician will use a DVOM to diagnose this OBD problem. The main focus of technician’s attention is to be on the circuit between the ECM and the VVT solenoid valve, as well as the solenoid valve itself.

• Connector and Harness Check – The technician should check that the VVT solenoid valve connector for being good, having no bent or back-out pins, corrosion, or water entry. Make sure the connector is firmly seated. Check the wire harness for damaged, chafing, exposed or broken wiring and harness. Repair as necessary.
• Voltage Check – A minimum 13.4 V at the battery is required when the engine is running. VVT solenoid valve is to be back probed, usually located in the cylinder head or valve cover, and the battery is also to be checked for voltage.
• Suspect an open circuit between the ECM and the valve, if the voltage is incorrect. Connector is disconnected and rechecked for battery voltage. If incorrect, suspect an open circuit between the ECM and the valve. Inspect the wire harness and repair as necessary.
• If voltage is correct, suspect a ground problem. With the key off and engine off, disconnect the VVT solenoid valve connector and the ECM connector. Check both pins for short to each other and short to ground from the VVT solenoid valve connector. Measure the infinite resistance to ground and across the pins. If incorrect, suspect a short circuit. Repair as necessary. 

Common mistakes when diagnosing the P0085 code

Skipping the diagnostic steps and not following the order provided are the most common mistakes which can lead the misdiagnosis and unnecessary repairs and costs, which could have been avoided.