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P0079 Code Explained: Exhaust Valve Control Solenoid Circuit Low Bank 1 Causes, Symptoms & Fixes

P0079 code displayed on an OBD-II scanner with the Bank 1 exhaust valve control solenoid, low circuit voltage, grounded wiring, and exhaust camshaft actuator highlighted.

If your OBD-II scanner displays P0079, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a lower-than-expected electrical signal in the Bank 1 exhaust valve control solenoid circuit.

The generic OBD-II definition for P0079 is:

Exhaust Valve Control Solenoid Circuit Low Bank 1

Depending on the manufacturer or scan tool, the description may appear as:

P0079 is an electrical circuit code associated with the solenoid that controls oil flow to the Bank 1 exhaust camshaft actuator. The PCM uses this solenoid to advance or retard exhaust camshaft timing as part of the engine’s variable valve timing system.

On documented Hyundai applications, P0079 may be set when the exhaust valve control solenoid control circuit is shorted to ground. Manufacturer-specific detection logic and thresholds vary, so the correct wiring diagram remains essential.

Common causes include:

Possible symptoms include:

P0079 is generally considered a moderate-severity fault. The vehicle may remain drivable, but the PCM may disable exhaust camshaft adjustment and hold the camshaft in a default position until the circuit problem is repaired.

For additional diagnostic information, visit:

P0079 Quick Facts

ItemInformation
OBD-II CodeP0079
DescriptionExhaust Valve Control Solenoid Circuit Low Bank 1
CategoryPowertrain
SystemVariable Valve Timing
Main ComponentExhaust Valve Control Solenoid
Affected SideBank 1
Fault TypeLow Circuit Voltage
Common Electrical CauseShort to Ground
SeverityModerate
Safe to Drive?Sometimes, for a short distance
Typical Repair Cost$100–700

What Does P0079 Mean?

P0079 means the PCM has detected an electrical value below its calibrated operating range in the Bank 1 exhaust valve control solenoid circuit.

The monitored circuit may include:

Depending on the electrical design, a low circuit condition may indicate:

A logged P0079 code generally means there is a low-voltage electrical problem affecting the Bank 1 exhaust valve control solenoid circuit.

P0079 should be diagnosed electrically before replacing camshaft phasers, timing chains, or other mechanical components.

Important Correction: P0078 vs P0079 vs P0080

The correct generic sequence is:

CodeDescription
P0078Exhaust Valve Control Solenoid Circuit Bank 1
P0079Exhaust Valve Control Solenoid Circuit Low Bank 1
P0080Exhaust Valve Control Solenoid Circuit High Bank 1

Therefore:

P0079 is not normally the intermittent version of P0078. It specifically refers to a low electrical signal in the exhaust valve control solenoid circuit.

What Is Bank 1?

Bank 1 is the side of the engine containing cylinder number 1.

On an inline engine, there is only one cylinder bank, so the entire engine is considered Bank 1.

On V-type engines, such as a:

Bank 1 may be on either side of the engine.

It is not automatically:

Consult:

to identify the correct bank.

Replacing the solenoid on the easier-to-reach side is not a diagnostic strategy, although it has funded an impressive number of unnecessary parts purchases.

What Is an Exhaust Valve Control Solenoid?

The exhaust valve control solenoid is an electrically operated oil-control valve used by the engine’s variable valve timing system.

Depending on the manufacturer, it may also be called:

The solenoid controls pressurized engine oil flowing to the exhaust camshaft actuator or cam phaser.

By changing that oil flow, the PCM can adjust exhaust camshaft timing according to:

Exhaust camshaft timing can influence:

P0079 means the PCM has detected an electrical problem controlling this solenoid—not necessarily a failed camshaft or timing chain.

How Variable Valve Timing Works

A typical variable valve timing system includes:

  1. Engine oil supply
  2. Oil passages in the cylinder head
  3. Exhaust valve control solenoid
  4. Exhaust camshaft actuator or phaser
  5. Camshaft position sensor
  6. Crankshaft position sensor
  7. PCM control strategy

When the PCM requests a camshaft adjustment:

If the electrical circuit remains too low, the PCM may disable variable valve timing and store P0079.

How the Exhaust Valve Control Solenoid Circuit Works

Many exhaust VVT solenoids use two wires.

A common low-side-controlled system includes:

The PCM controls the solenoid using pulse-width modulation.

Rather than simply switching the solenoid fully on or off, it rapidly switches the circuit to regulate:

The PCM may monitor:

If the PCM detects the circuit is pulled too close to ground or draws excessive current, it may set P0079.

Some applications define P0079 specifically as a short-to-ground condition in the exhaust valve control solenoid circuit.

What Does “Circuit Low” Mean?

“Circuit low” refers to the electrical voltage or driver feedback, not the oil level or camshaft position.

It does not automatically mean:

Common circuit-low conditions include:

A shorted control circuit may cause the solenoid to remain:

The exact result depends on circuit design.

P0078 vs P0079 vs P0080

CodeDescriptionTypical Meaning
P0078Exhaust Valve Control Solenoid Circuit Bank 1General circuit malfunction
P0079Exhaust Valve Control Solenoid Circuit Low Bank 1Circuit voltage below specification
P0080Exhaust Valve Control Solenoid Circuit High Bank 1Circuit voltage above specification

Related Bank 2 exhaust-solenoid codes include:

CodeDescription
P0084Exhaust Valve Control Solenoid Circuit Bank 2
P0085Exhaust Valve Control Solenoid Circuit Low Bank 2
P0086Exhaust Valve Control Solenoid Circuit High Bank 2

P0079 vs P0013

P0013 is generally defined as:

“B” Camshaft Position Actuator Circuit Bank 1

P0079 is defined as:

Exhaust Valve Control Solenoid Circuit Low Bank 1

Both codes may involve the Bank 1 exhaust camshaft oil-control solenoid.

The difference is that:

Manufacturer terminology varies, so follow the diagnostic procedure written for the exact code, engine, and model year.

How the PCM Detects P0079

The PCM may set P0079 when:

On one documented Hyundai strategy, P0079 is detected through an electrical check when the exhaust valve control solenoid control circuit is shorted to ground. The listed diagnostic time is approximately two seconds under valid battery-voltage conditions, although these details are application-specific.

The PCM may respond by:

Symptoms of P0079

Possible symptoms include:

Poor acceleration and reduced fuel economy are commonly associated with P0079 because the PCM may disable variable valve timing when it detects the low circuit condition.

The severity depends on:

Can P0079 Cause a Rough Idle?

Yes.

Incorrect exhaust camshaft timing can affect:

Possible results include:

However, rough idle may also be caused by:

Confirm that the P0079 circuit problem is active before attributing every idle complaint to the exhaust VVT solenoid.

Can P0079 Cause Poor Acceleration?

Yes.

Exhaust camshaft timing contributes to:

When exhaust VVT is disabled, the engine may feel:

Poor acceleration is a recognized P0079 symptom.

Common Causes of P0079

1. Exhaust VVT Solenoid Shorted Internally

The solenoid’s internal coil may short between windings.

This can produce:

An internally shorted solenoid is one of the most common direct causes of a circuit-low code.

2. Control Wire Shorted to Ground

The PCM-controlled wire may rub through its insulation and touch:

A documented manufacturer-specific P0079 definition identifies a control-circuit short to ground as a primary detection condition.

3. Melted Engine Wiring

The exhaust solenoid is often located near high-temperature components.

Wiring may be damaged by:

Melted insulation may allow:

4. Chafed Wiring Harness

The wiring may rub against:

Engine vibration can gradually wear through the insulation.

The harness does not need to look dramatically destroyed. One exposed copper strand touching the cylinder head is enough to create an electrical shortcut.

5. Failed Exhaust Valve Control Solenoid

The solenoid may fail because of:

Electrical testing may reveal:

6. Corroded Connector Terminals

Corrosion can create:

Inspect for:

Poor connectors and wiring problems are recognized common P0079 causes.

7. Oil-Contaminated Connector

Oil may enter the connector because of:

Oil can:

Repair the source of the leak rather than cleaning the connector and sending it back into the same oil bath.

8. Water Intrusion

Water may enter through:

Moisture may bridge the terminals and create a low-resistance path to ground.

9. Connector Terminals Shorted Together

Bent terminals, moisture, metal debris, or damaged insulation may connect:

Inspect terminal spacing and connector condition carefully.

10. Incorrectly Wired Replacement Pigtail

A replacement connector may have:

Verify the pinout using the wiring diagram.

Matching colors is not enough when the replacement pigtail manufacturer selected different colors—or when the previous technician treated wire identification as a creative exercise.

11. Missing Solenoid Power Supply

Depending on circuit design, missing supply voltage may create a low monitored value.

Possible causes include:

If several VVT or actuator codes appear together, inspect shared power supplies before replacing multiple solenoids.

12. Blown Fuse

A fuse may blow because of:

Do not repeatedly replace a blown fuse.

A fuse does not fail from boredom. It is usually reacting to excessive current somewhere downstream.

13. Failed Engine-Control Relay

A damaged relay may cause:

Inspect the relay if it supplies:

14. High Resistance in the Power Circuit

A circuit may show voltage on a multimeter but collapse under load because of:

A voltage-drop or loaded-circuit test is more useful than an unloaded continuity check.

15. Poor PCM or Engine Ground

A poor ground may interfere with:

Inspect:

Multiple unrelated circuit-low codes make a shared ground problem more likely.

16. Low Battery or Charging Voltage

A weak battery or charging fault may contribute to abnormal actuator operation.

Check:

Low system voltage is less likely when P0079 is the only code, but it should be considered when several circuit-low codes appear together.

17. Low Engine Oil Level

Low oil does not usually create the electrical low signal directly.

However, the exhaust VVT system depends on engine oil to move the camshaft actuator.

Low oil may cause:

Always check oil level before performing VVT command tests.

18. Dirty or Sludged Engine Oil

Contaminated oil may restrict:

Dirty oil may cause timing-performance codes in addition to P0079.

It will not repair a grounded control wire, but it can ensure the VVT system still performs badly after the wiring fault is fixed.

19. Incorrect Oil Viscosity

Oil that is too thick or too thin can cause:

Use the manufacturer-specified oil viscosity and standard.

20. Clogged Solenoid Screen

Some exhaust VVT solenoids contain a fine oil screen.

The screen may become blocked by:

A clogged screen is primarily a hydraulic performance problem, but contamination may coexist with an electrically failed solenoid.

21. Incorrect Replacement Solenoid

An incorrect solenoid may have:

A new part can still be:

Fresh packaging is not a diagnostic measurement.

22. PCM Software Issue

A calibration problem may cause the PCM to:

Check for:

Software problems are less common than wiring, connector, and solenoid faults.

23. Failed PCM Driver

The internal PCM driver may fail because of:

Only suspect the PCM after confirming:

Replacing the PCM before testing the two-wire solenoid circuit is an efficient way to turn a grounded wire into a four-figure repair that still does not work.

Is P0079 Serious?

P0079 is generally considered a moderate-severity code.

The engine may continue running, but exhaust camshaft adjustment may be:

Possible consequences include:

P0079 becomes more serious if:

Can You Drive With P0079?

You may be able to drive a short distance if:

Avoid continued driving if:

A disabled VVT system may not immediately damage the engine.

A shorted wire heating against the cylinder head deserves considerably less patience.

How to Diagnose P0079

Step 1: Scan Every Stored Code

Check for:

Record:

Multiple circuit-low codes may indicate a shared power or ground problem.

Step 2: Confirm the Code Definition

Verify that the scanner identifies P0079 as:

Exhaust Valve Control Solenoid Circuit Low Bank 1

Do not confuse it with:

P0079 is specifically a circuit-low code.

Step 3: Identify Bank 1

Locate:

Do not confuse:

Step 4: Check Engine Oil Level

Park on level ground and check:

Correct low oil before operating the VVT system.

Step 5: Inspect Oil Condition

Look for:

Perform an oil and filter change if needed, but continue electrical testing because P0079 identifies a circuit-low fault.

Step 6: Locate the Exhaust Valve Control Solenoid

The solenoid may be installed:

Confirm the component using service information.

Step 7: Inspect the Solenoid Connector

Check for:

Repair connector problems before replacing the solenoid.

Step 8: Inspect the Wiring Harness

Follow the wiring toward:

Look for:

Step 9: Check Shared Fuses and Relays

Identify the fuse and relay supplying the exhaust solenoid.

If the fuse is blown:

  1. Disconnect the solenoid.
  2. Measure solenoid resistance.
  3. Check the supply wire for a short.
  4. Inspect other actuators sharing the fuse.
  5. Repair the electrical fault.
  6. Install the correct fuse rating.
  7. Retest the circuit.

Never install a larger fuse.

That does not increase reliability. It merely allows the wiring harness to audition for the role of the fuse.

Step 10: Measure Solenoid Resistance

Disconnect the solenoid and measure resistance across its terminals.

Compare the result with manufacturer specifications.

Possible findings include:

Do not use a generic resistance specification from a different vehicle.

Step 11: Check for a Short to the Solenoid Housing

When permitted by service information, measure resistance between:

Unexpected continuity may indicate an internal short.

Step 12: Disconnect the Solenoid and Observe Circuit Status

With the solenoid unplugged, monitor the circuit using:

If the low condition changes to high or open:

If the circuit remains low with the solenoid unplugged:

Interpret results using the exact circuit design.

Step 13: Verify Supply Voltage

With ignition on, test the solenoid power terminal.

Expected voltage may be:

If voltage is missing, inspect:

Step 14: Load-Test the Supply Circuit

An unloaded circuit may show normal voltage through a corroded connection.

Perform an approved loaded test to check:

A voltage collapse under load indicates excessive resistance.

Step 15: Test the PCM Control Wire for a Short to Ground

Disconnect the PCM and solenoid as instructed.

Measure resistance between:

Unexpected continuity indicates a short-to-ground condition.

Move the harness during testing because the short may occur only when the wire touches a bracket.

Step 16: Check for a Short Between Circuits

Test whether the control circuit is contacting:

Melted harness sections may connect several circuits together.

Step 17: Check Circuit Continuity

Test both wires from the solenoid connector to their destinations.

Inspect for:

Circuit resistance should meet manufacturer specifications.

Step 18: Perform Voltage-Drop Tests

With the circuit commanded on, measure voltage drop across:

Excessive voltage drop indicates unwanted resistance.

Step 19: Command the Solenoid With a Scan Tool

Use a bidirectional scan tool when supported.

Monitor:

Possible results include:

Step 20: Use a Current Clamp

A low-current clamp can help evaluate solenoid operation without opening the circuit.

Possible findings include:

Compare the waveform with:

Step 21: Examine the PWM Signal

An oscilloscope can display:

A waveform stuck near ground may indicate:

Step 22: Perform a Wiggle Test

Monitor circuit voltage and current while moving:

Watch for:

Step 23: Inspect the Solenoid Mechanically

If electrical testing passes, remove the solenoid according to the repair procedure.

Inspect for:

Mechanical restrictions generally cause performance codes, but they may coexist with P0079.

Step 24: Compare Bank 1 With Bank 2

On engines with two banks, compare:

A healthy Bank 2 circuit may provide a valuable reference.

Confirm that both sides use the same component before comparing resistance or swapping parts.

Step 25: Swap Solenoids Only When Approved

If the Bank 1 and Bank 2 exhaust solenoids are identical, a controlled swap may help isolate the fault.

After swapping:

Do not swap intake and exhaust solenoids unless the manufacturer confirms they are interchangeable.

Step 26: Check PCM Power and Grounds

Before condemning the PCM, verify:

A poor PCM ground can create misleading driver-circuit faults.

Step 27: Check Technical Service Bulletins

Search manufacturer information using:

Possible factory corrections include:

Step 28: Evaluate the PCM Driver

Only evaluate PCM failure after confirming:

If the PCM driver remains grounded or cannot control the circuit after all external tests pass, the PCM may require:

Step 29: Verify the Repair

After completing repairs:

  1. Clear all diagnostic trouble codes.
  2. Start the engine.
  3. Confirm the oil-pressure warning light turns off normally.
  4. Monitor the Bank 1 exhaust solenoid command.
  5. Check circuit voltage and current.
  6. Compare desired and actual exhaust camshaft timing.
  7. Verify normal idle quality.
  8. Road-test under varied load and RPM.
  9. Complete the required drive cycle.
  10. Rescan for pending and confirmed codes.
  11. Confirm P0079 does not return.

Common Repairs and Costs

RepairEstimated Cost
Reconnect or reseat connector$0–100
Clean electrical connector$50–150
Replace connector terminals$75–250
Engine oil and filter change$60–180
Replace exhaust VVT solenoid$150–500
Repair shorted wiring$150–650
Replace solenoid connector$100–325
Replace fuse or relay after repairing fault$75–250
Repair engine power-supply circuit$150–700
Clean restricted oil passage$200–700
Replace camshaft actuator or phaser$700–2,000+
Replace timing-chain components$1,000–4,000+
Update PCM software$100–300
Replace and program PCM$1,000–2,500+

Actual cost depends on:

A shorted solenoid mounted at the top of the cylinder head may be straightforward.

A grounded control wire buried beneath the intake manifold may require dismantling half the engine bay to reach the automotive equivalent of one bad extension cord.

Common Diagnostic Mistakes

Avoid these common P0079 diagnostic mistakes:

P0079 is an electrical circuit-low code.

The timing chain may eventually require service, but replacing it because one wire is touching the cylinder head is an impressively expensive misunderstanding.

Vehicles Commonly Affected

P0079 is a generic OBD-II code and may appear on various vehicles, including certain:

Manufacturer terminology may include:

P0079 is particularly documented on Hyundai and Kia applications, where it may indicate the exhaust oil-control-valve circuit is shorted to ground.

P0079 on Hyundai and Kia Vehicles

Hyundai and Kia may refer to the component as the:

On certain applications, the PCM uses pulse-width modulation to control the oil control valve and monitors the circuit for a short to ground.

Common inspection areas include:

A documented Hyundai diagnostic reference lists a short to ground, damaged harness, poor connection, or faulty exhaust valve control solenoid among possible P0079 causes.

P0079 on Nissan and Infiniti Vehicles

Nissan and Infiniti may refer to the component as the:

Exhaust Valve Timing Control Solenoid Valve

Possible causes include:

Check oil condition and pressure if additional exhaust camshaft timing-performance codes are present.

P0079 After Engine Repairs

If P0079 appears after:

inspect for:

A code that appears immediately after repair work should be investigated first in the area that was disturbed.

The PCM may control valve timing thousands of times per minute, but it remains unable to reroute a wire that was crushed during yesterday’s valve-cover job.

P0079 After a Blown Fuse

If the actuator or engine-control fuse is blown:

  1. Disconnect the Bank 1 exhaust VVT solenoid.
  2. Measure solenoid resistance.
  3. Test the power wire for a short to ground.
  4. Inspect other actuators sharing the fuse.
  5. Check wiring near hot and moving components.
  6. Repair the fault.
  7. Install the correct fuse.
  8. Monitor current while commanding the circuit.

Never substitute a higher-amperage fuse.

The original fuse was attempting to protect the harness. Overruling it does not improve the diagnosis.

Can Dirty Oil Cause P0079?

Dirty oil may contribute to VVT performance problems, but P0079 specifically indicates a low electrical circuit condition.

Dirty oil may cause:

It generally does not directly cause:

Check oil condition, but do not abandon electrical testing because the oil is dark.

Can a Bad VVT Solenoid Cause P0079?

Yes.

A failed exhaust VVT solenoid can cause P0079 if its internal coil:

Measure resistance and current rather than replacing the solenoid solely because its name appears in the code.

Can a Bad Camshaft Position Sensor Cause P0079?

A camshaft position sensor is not a common direct cause of P0079.

The camshaft sensor reports camshaft position, while P0079 monitors the exhaust valve control solenoid circuit.

A failed camshaft sensor is more likely to set:

Diagnose all stored codes together.

How to Prevent P0079

Reduce the likelihood of P0079 by:

Frequently Asked Questions

What does P0079 mean?

P0079 means the PCM has detected a lower-than-expected electrical signal in the Bank 1 exhaust valve control solenoid circuit.

What is the full definition of P0079?

The generic definition is:

Exhaust Valve Control Solenoid Circuit Low Bank 1

Is P0079 an intermittent circuit code?

No.

P0079 is normally the circuit-low code.

The sequence is:

Where is Bank 1?

Bank 1 is the side of the engine containing cylinder number 1.

Inline engines have only one bank, which is Bank 1.

What does circuit low mean?

Circuit low means the monitored voltage or driver feedback is below the PCM’s expected range.

It commonly indicates:

Does circuit low mean the engine oil is low?

No.

The word “low” refers to the electrical circuit.

Low oil may cause related VVT performance problems but is not the same condition.

What causes P0079 most often?

Common causes include:

Is P0079 serious?

P0079 is moderately serious.

The vehicle may remain drivable, but engine performance, fuel economy, idle quality, and emissions may suffer.

Can I drive with P0079?

Possibly for a short distance if:

Stop driving if the oil-pressure warning appears, the engine rattles, it stalls, or power loss becomes severe.

Can P0079 cause rough idle?

Yes.

Incorrect exhaust camshaft timing may create rough idle, surging, misfires, or stalling.

Can P0079 cause poor acceleration?

Yes.

Loss of exhaust camshaft control can reduce torque, throttle response, and turbocharger performance.

Can P0079 blow a fuse?

Yes.

An internally shorted solenoid or grounded supply wire may blow a shared actuator fuse.

Can dirty oil cause P0079?

Dirty oil can create hydraulic VVT problems, but P0079 requires electrical testing because it identifies a circuit-low condition.

What is the difference between P0078 and P0079?

P0078 indicates a general Bank 1 exhaust valve control solenoid circuit malfunction.

P0079 specifically indicates a low circuit condition.

What is the difference between P0079 and P0080?

P0079 indicates circuit voltage below specification.

P0080 indicates circuit voltage above specification.

Can I test the solenoid with a multimeter?

Yes.

Common tests include:

Use vehicle-specific specifications.

Can I apply battery voltage directly to the solenoid?

Only when the manufacturer’s procedure permits it.

Incorrect polarity, excessive voltage, or continuous power may damage the solenoid or PCM circuit.

Does a new exhaust VVT solenoid require programming?

Usually not.

The vehicle may require:

A replacement PCM requires programming.

How much does P0079 cost to repair?

A typical exhaust VVT solenoid replacement costs approximately $150–500.

Wiring, fuse-box, camshaft actuator, timing-chain, or PCM repairs may cost substantially more.

Final Thoughts

The P0079 code means the PCM has detected a low electrical condition in the Bank 1 exhaust valve control solenoid circuit.

The most common causes include:

Start diagnosis by:

  1. Confirming P0079 is the circuit-low code.
  2. Scanning for related codes.
  3. Identifying Bank 1 correctly.
  4. Checking oil level and condition.
  5. Inspecting the exhaust solenoid connector.
  6. Examining the harness for grounded wiring.
  7. Measuring solenoid resistance.
  8. Checking the fuse and relay.
  9. Verifying supply voltage.
  10. Testing the PCM control circuit for a short to ground.
  11. Commanding the solenoid with a bidirectional scan tool.

Do not interpret “circuit low” as proof that the engine simply needs more oil.

The engine does need the correct oil, but P0079 is warning that the electrical side of the Bank 1 exhaust VVT system has fallen below specification.

The eventual repair may be a shorted solenoid, damaged connector, blown fuse, failed relay, grounded wire, or PCM driver problem.

Variable valve timing may involve hydraulic actuators, computer-controlled duty cycles, camshaft feedback, and enough technical vocabulary to sound expensive.

Sometimes, however, the entire system stops working because one wire rubbed against a metal bracket until it discovered ground.

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