P0086 Exhaust Valve Control Solenoid Circuit High (Bank 2)

P0086 is an engine management fault code associated with the exhaust valve control solenoid circuit on Bank 2. The engine control module (ECM/PCM) has detected an electrical signal in this solenoid circuit that is higher than the expected range.

The important point is that P0086 is primarily an electrical circuit diagnosis. The code does not automatically mean that the exhaust valve control solenoid itself has failed, nor does it necessarily indicate a mechanical problem with the engine's exhaust valves.

The exact system referred to by “exhaust valve control” can vary considerably between manufacturers. On some engines it may relate to a variable valve timing (VVT) or camshaft control solenoid, while on other applications it can refer to a different electronically controlled exhaust-valve mechanism. Therefore, the manufacturer's wiring diagram and component identification are important before testing.

What Does P0086 Mean?

The code can be broken down into several parts:

• P – Powertrain

• 00 – Generic OBD-II code

• 86 – Specific fault identifier

• Exhaust Valve Control Solenoid – The electronically controlled component identified by the vehicle manufacturer

• Circuit High – The ECM/PCM has detected a voltage or electrical condition above the expected range

• Bank 2 – The cylinder bank that does not contain cylinder number 1

The phrase “Circuit High” is particularly important.

It does not mean that exhaust temperature is too high, engine temperature is too high, or exhaust pressure is too high.

It means that the electrical circuit associated with the control solenoid is reporting a condition that the ECM considers excessively high.

What Is the Exhaust Valve Control Solenoid?

An electronically controlled exhaust-valve solenoid is used to regulate or control a mechanism associated with the engine's exhaust valve timing or exhaust-side valve operation.

On engines equipped with variable valve timing, for example, the ECM may control an oil-control solenoid to alter camshaft position. Changing exhaust camshaft timing can influence:

• Valve overlap

• Exhaust gas flow

• Torque production

• Engine efficiency

• Emissions

• Turbocharger response on some engines

• Idle quality

The ECM does not simply turn the solenoid on and leave it there. Depending on the system, it can use a duty-cycle-controlled signal to regulate the solenoid.

The ECM then monitors the electrical response and, in many systems, checks whether the resulting camshaft position agrees with the commanded position.

This creates several possible failure points:

ECM command → wiring → connector → solenoid → hydraulic/mechanical mechanism → position feedback

P0086 specifically points toward the electrical side of this chain, but the complete system still needs to be considered during diagnosis.

What Does “Bank 2” Mean?

Bank 2 is the cylinder bank that does not contain cylinder number 1.

On a V6, V8 or other multi-bank engine, there are normally two cylinder banks, so Bank 1 and Bank 2 are physically different sides of the engine.

On an inline four-cylinder engine there is normally only one cylinder bank, so a Bank 2 code would generally not apply unless the manufacturer uses a special configuration or system.

It is important not to interpret Bank 2 as “cylinder number 2.”

Bank 2 does not mean cylinder 2.

The physical location of the Bank 2 exhaust valve control solenoid should therefore be confirmed using the vehicle-specific service information.

What Does “Circuit High” Actually Tell You?

This is where P0086 is often misunderstood.

A high circuit signal can occur for several different electrical reasons.

For example, depending on the circuit design, the ECM may detect high voltage because of:

• An open control wire

• A disconnected solenoid

• A broken wire

• A poor terminal connection

• A short to battery voltage

• A failed solenoid with an abnormal internal circuit

• A missing electrical load

• A problem with the ECM driver circuit

• A power supply problem

• A wiring fault near the exhaust

• Corrosion inside the connector

Therefore, simply replacing the solenoid is not a complete diagnosis.

Common Symptoms of P0086

The symptoms depend heavily on the engine and the exact valve-control system involved.

Some vehicles may continue to run almost normally, while others can experience noticeable drivability problems.

Possible symptoms include:

• Check Engine Light

• Rough or unstable idle

• Reduced engine performance

• Hesitation during acceleration

• Poor throttle response

• Reduced fuel economy

• Difficulty starting

• Engine stalling

• Poor low-speed torque

• Poor high-RPM performance

• Variable valve timing warning

• Reduced-power or fail-safe operation

• Increased emissions

• Additional camshaft timing codes

Some vehicles may also exhibit a noticeable difference between cold and hot operation.

If the system depends on engine oil pressure for variable valve timing, an electrical solenoid fault can sometimes be accompanied by timing-related performance problems because the commanded valve timing is no longer achieved correctly.

The Most Common Causes of P0086

There are several possible causes, and they should not all be treated equally.

1. Faulty exhaust valve control solenoid

The solenoid itself can develop an internal electrical problem.

Its coil may become open-circuit, shorted, or develop resistance outside the manufacturer's specification.

However, the solenoid should be tested before being condemned.

2. Open circuit in the wiring

A broken wire can cause the ECM to see an unexpectedly high voltage.

This is especially important because wiring around the cylinder head and exhaust side of the engine is exposed to:

• High temperatures

• Vibration

• Oil

• Moisture

• Mechanical movement

• Previous repairs

A wire may look intact externally while being broken internally.

3. Short to battery voltage

A control wire that should normally be switched by the ECM can become connected to a higher-voltage supply.

This can create a genuine “circuit high” condition.

Finding the exact location of the short requires a wiring diagram and circuit testing.

4. Damaged connector

A loose, corroded, bent or pushed-back terminal can interrupt the solenoid circuit.

The connector may appear physically connected while the terminal does not make proper electrical contact.

Terminal tension is therefore important.

5. Poor power or ground

Depending on the electrical architecture, the solenoid may share power, ground or reference circuitry with other components.

A poor connection can cause abnormal electrical behavior and sometimes multiple related fault codes.

6. Oil contamination or mechanical sticking

This is particularly relevant when the solenoid controls variable valve timing.

Dirty engine oil, sludge or contamination can cause a control solenoid or its associated hydraulic mechanism to stick.

However, a mechanically restricted solenoid does not automatically explain an electrical circuit-high code. The electrical fault and mechanical fault should be distinguished.

7. ECM/PCM driver problem

The ECM controls the solenoid through an internal driver circuit.

A failed driver is possible, but it should normally be considered after the external wiring, connector, power supply and solenoid have been properly tested.

Replacing the ECM simply because P0086 is present is not a good diagnostic strategy.

P0086 and Variable Valve Timing

On many applications, the exhaust-side control solenoid is associated with variable valve timing.

The ECM may request a particular camshaft position according to:

• Engine speed

• Engine load

• Coolant temperature

• Accelerator position

• Throttle position

• Operating conditions

• Emissions strategy

The solenoid then controls oil flow to the camshaft phaser.

If the solenoid circuit has an electrical problem, the ECM may lose the ability to control the exhaust camshaft correctly.

This can lead to additional codes related to:

• Camshaft position

• Camshaft timing

• VVT performance

• Camshaft/crankshaft correlation

This is why it is important to scan for all stored and pending codes, rather than diagnosing P0086 in isolation.

How to Diagnose P0086 Correctly

A good diagnosis starts with the electrical circuit rather than immediately replacing components.

Start with a complete scan

Record all:

• Stored DTCs

• Pending DTCs

• Manufacturer-specific codes

• Freeze-frame information

If there are additional camshaft, VVT, low-voltage or communication codes, they may significantly change the diagnostic direction.

Check the freeze-frame data

Look at the conditions under which P0086 was set.

Useful information can include:

• Engine RPM

• Coolant temperature

• Engine load

• Vehicle speed

• Battery voltage

• Throttle position

• Camshaft position

• Requested valve timing

A code occurring immediately after startup may have a different cause from one appearing only at high engine speed.

Inspect the Solenoid and Connector

Before using sophisticated equipment, perform a careful physical inspection.

Look for:

• Melted insulation

• Oil inside the connector

• Corrosion

• Broken connector locks

• Bent terminals

• Loose terminals

• Wiring touching the exhaust

• Harness damage

• Previous repair work

• Stretched wiring

• Evidence of water intrusion

Pay particular attention to areas where the harness passes close to hot engine components.

A connector that looks clean is not necessarily electrically healthy.

Check the Solenoid's Electrical Characteristics

The resistance of the solenoid can be measured if the manufacturer provides a resistance specification.

Do not use a generic resistance value simply because another engine uses a similar-looking solenoid.

Different systems use different coil designs and control strategies.

A resistance measurement can identify an obvious open or shorted coil, but it does not always prove that the solenoid works correctly under operating conditions.

For example, a solenoid may have acceptable static resistance but still have:

• Intermittent internal faults

• Mechanical sticking

• Heat-related failure

• Poor terminal contact

Check Power and Control Signals

The next step is to determine how the particular vehicle controls the solenoid.

Some systems provide a constant power supply and allow the ECM to switch the control side.

Other systems use different driver configurations.

The wiring diagram is therefore essential.

Depending on the system, testing may include:

• Supply voltage

• Control voltage

• Ground

• Voltage drop

• Continuity

• Short-to-ground testing

• Short-to-power testing

• Control signal testing

• Current draw

Continuity alone is not enough.

A wire can show continuity with a multimeter and still fail when current flows through it or when the harness moves.

Voltage-drop testing under load can reveal problems that a simple continuity check misses.

Use a Scan Tool to Check Commanded Operation

A capable diagnostic scanner can make the diagnosis much faster.

If the vehicle supports active testing, the technician may be able to command the exhaust valve control solenoid.

During the test, observe:

• Solenoid command

• Electrical response

• Camshaft commanded position

• Camshaft actual position

• Engine RPM

• Oil temperature

• Related VVT parameters

If the ECM commands the solenoid but the electrical response is incorrect, concentrate on the circuit.

If the electrical response is correct but camshaft movement does not follow the command, the problem may be hydraulic or mechanical rather than purely electrical.

Don't Ignore Engine Oil

When P0086 involves a VVT solenoid, engine oil condition becomes relevant.

Check:

• Correct oil level

• Correct oil viscosity

• Oil condition

• Oil change history

• Sludge contamination

• Oil pressure where necessary

A restricted oil passage can interfere with camshaft timing.

However, low engine oil should not automatically be blamed for a circuit-high fault.

The electrical circuit still needs to be tested.

Check Camshaft and Crankshaft Data

If the system uses variable valve timing, compare the commanded and actual camshaft positions.

A useful diagnostic question is:

Does the ECM command the exhaust camshaft to move, and does the camshaft actually move as expected?

If the command changes but the actual position remains fixed, investigate:

• Solenoid operation

• Oil supply

• Camshaft phaser

• VVT mechanism

• Mechanical timing

• Camshaft position sensor

• Related wiring

If the electrical circuit itself is incorrect, focus on the circuit before replacing mechanical components.

Could a Camshaft Sensor Cause P0086?

It can be relevant to the overall diagnosis, but it should not automatically be blamed.

A camshaft position sensor provides feedback about camshaft position.

A control solenoid, on the other hand, is an actuator.

They perform different jobs.

A vehicle can therefore have a perfectly good camshaft sensor but a faulty solenoid circuit, or a good solenoid circuit but a camshaft position problem.

If P0086 appears together with camshaft position or correlation codes, the sensor and mechanical timing should be investigated as part of the complete system.

Could Low Engine Oil Cause P0086?

Low or degraded oil can contribute to VVT problems on engines that use oil pressure for camshaft control.

However, there is an important distinction:

Low oil can cause poor VVT operation, but P0086 specifically identifies an electrical circuit-high condition.

Therefore, checking the oil is sensible, but it should not replace electrical diagnosis.

If the electrical circuit is open, shorted or disconnected, correcting the oil level will not repair the circuit.

Could P0086 Be Caused by a Bad Solenoid?

Yes.

But the code does not prove that the solenoid is bad.

The ECM sees an abnormal electrical condition and reports the circuit code. The actual cause could be:

• Solenoid

• Connector

• Wiring

• Power supply

• Control circuit

• ECM driver

This distinction is important because replacing a solenoid when the real problem is a broken wire will not solve the fault.

A Useful Diagnostic Strategy

A practical diagnostic sequence for P0086 is:

1. Scan all vehicle modules and record every code.

2. Save freeze-frame information.

3. Confirm the exact definition and location of the Bank 2 exhaust control solenoid.

4. Inspect the solenoid and connector.

5. Inspect the harness for heat and mechanical damage.

6. Identify the circuit architecture from the wiring diagram.

7. Check power and ground.

8. Test the control circuit for opens and shorts.

9. Measure solenoid resistance if specified.

10. Perform voltage-drop and load testing.

11. Use an active test if supported.

12. Compare commanded and actual camshaft positions where applicable.

13. Check engine oil condition and VVT hydraulic operation.

14. Investigate mechanical timing if the evidence points in that direction.

15. Consider the ECM only after the external circuit and component tests are satisfactory.

This sequence prevents a common diagnostic mistake: replacing expensive parts before proving where the electrical fault actually exists.

What Happens If You Continue Driving With P0086?

The seriousness depends on the vehicle and the symptoms.

If the engine runs normally and the Check Engine Light is steady, the vehicle may remain driveable for a limited period.

However, continued operation can result in:

• Poor fuel economy

• Reduced performance

• Increased emissions

• Poor idle quality

• Additional timing-related faults

• Reduced-power operation

• Catalyst stress if combustion becomes abnormal

If the vehicle develops severe hesitation, stalling, significant power loss, loud mechanical noise, or a flashing Check Engine Light, driving should be minimized.

A flashing warning can indicate a serious engine-management problem, particularly if misfire is occurring.

Final Diagnosis

P0086 means the ECM/PCM has detected a high electrical condition in the exhaust valve control solenoid circuit on Bank 2.

The key word is “circuit.”

The correct diagnosis should therefore begin with the solenoid connector, wiring, power supply, control signal and electrical load before assuming the solenoid itself has failed.

If the system is part of variable valve timing, the diagnosis should then continue into commanded versus actual camshaft position, oil supply and the mechanical VVT mechanism.

The most important rule is simple:

Do not interpret P0086 as “replace the exhaust valve control solenoid.” Interpret it as “find out why the solenoid circuit is electrically higher than the ECM expects.”

That approach can prevent unnecessary solenoid, camshaft, VVT and even ECM replacement.