P0079 — Exhaust Valve Control Solenoid Circuit Low (Bank 1)

P0079 — Exhaust Valve Control Solenoid Circuit Low (Bank 1). A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: control module driver fault, faulty sensor or actuator of the affected circuit, corroded, loose or damaged connector.

powertrain (engine/transmission)

Is it safe to drive?

Drive cautiously to repair P0079 usually allows limited driving if the engine runs smoothly and temperatures remain stable. Avoid extended driving if there is severe roughness, misfire, major power loss, overheating, or an oil-pressure warning; those conditions require immediate attention.

Typical symptoms

The check engine light or malfunction indicator lamp illuminates with P0079
Rough idle, hesitation, or noticeable loss of power may occur
Exhaust valve timing response may be slow or restricted on engines using variable valve timing
Unusual engine noise can accompany incorrect valve timing operation
Long-term fuel-trim corrections may be stored in the powertrain controller
Some vehicles enter a reduced-power mode when P0079 is active

Common causes

A failed or internally shorted Bank 1 exhaust valve control solenoid
Open or high-resistance wiring in the solenoid control circuit
Corroded, loose, or pushed-back terminals in the solenoid connector
A short to ground that collapses the control-circuit voltage when commanded
Poor engine grounding or excessive voltage drop in the control circuit
A faulty powertrain control module driver for the Bank 1 circuit
An incorrectly installed or mismatched replacement solenoid

How to diagnose with an OBD scanner

Confirm P0079 and capture freeze-frame data Connect an OBD2 scanner, ELM327 adapter, or compatible AIScanAuto tool to the diagnostic port. Read the powertrain codes and confirm that P0079 is current or pending, then save freeze-frame data for battery voltage, engine speed, and operating conditions.
Inspect the Bank 1 solenoid and connector Using service information, identify the Bank 1 exhaust valve control solenoid. Inspect its connector for corrosion, water intrusion, bent pins, loose locking tabs, and separated or chafed wiring near the engine and exhaust heat shields.
Check power, ground, and circuit integrity Verify battery and charging-system voltage, then check the specified power and ground terminals for voltage drop. Inspect the wiring for opens, shorts to ground, and heat damage; repair damaged conductors or terminals before condemning the solenoid.
Measure the solenoid control signal Follow the manufacturer wiring diagram and back-probe the relevant terminals while P0079 is active. Compare the voltage and duty-cycle behavior with the commanded state and service specifications. A waveform or scope may be needed because some controllers use pulse-width-modulated signals.
Test or replace the solenoid Disconnect the component before resistance testing and compare its resistance with the service specification. Do not declare the solenoid defective from resistance alone. If the circuit readings are correct but the measured signal is abnormal, replace the solenoid with the specified part.
Clear and verify the repair After repairing the wiring, connector, ground, or solenoid, clear P0079 with the scanner. Road-test the vehicle under the conditions captured in the freeze frame, then confirm that P0079 does not return and that related powertrain codes and monitors remain normal.

Approximate repair cost

Typical independent-shop estimates are about $180–$800 for diagnosis and repair. A solenoid replacement commonly falls around $250–$600, while connector or wiring repairs may add approximately $80–$300. These USD figures are estimates and vary by region, vehicle configuration, and parts availability.

Common questions

Does P0079 mean the exhaust valve itself is stuck?

Not necessarily. P0079 identifies a low-voltage condition in the Bank 1 exhaust valve control solenoid circuit; a mechanically restricted valve may be a separate concern.

Can the vehicle be driven with P0079 stored?

A short trip to a repair shop is generally reasonable if power and engine operation remain normal, but driving should stop if overheating, severe roughness, or misfire develops.

What does Bank 1 mean in P0079?

Bank 1 identifies the engine bank containing cylinder 1. It is the side where the Bank 1 exhaust valve control solenoid and its wiring are located.

Can an ELM327 or AIScanAuto tool clear P0079?

Yes, a compatible tool can usually clear the code and display related data, but clearing it does not repair the circuit. Stored readiness information and adaptations may also be affected.

P0079 is a powertrain trouble code that points to a problem with the exhaust valve control solenoid circuit on Bank 1 of your engine. When the engine control module (ECM) detects that the electrical signal to this solenoid is running lower than expected, it logs P0079 and triggers the Check Engine light. The solenoid in question plays a role in managing exhaust valve timing or lift, which affects how efficiently the engine breathes — especially under varying load conditions. A weak or missing signal prevents the solenoid from operating as intended, which can throw off exhaust gas flow and reduce performance.

Bank 1 refers to the engine bank that contains cylinder number one. On V-type engines, this is the side where cylinder 1 sits; on inline engines, Bank 1 is simply the only bank present. Before diagnosing or replacing any components for P0079, confirm the cylinder-1 bank orientation for your specific engine configuration, because the other bank (Bank 2) uses separate wiring and sensors. The ECM does not flag P0079 based on a single bad reading. It requires multiple failed checks under specific operating conditions — load, rpm, temperature, and vehicle speed — before the light comes on. The freeze frame data stored alongside P0079 tells you exactly what was happening when the fault was recorded, which is invaluable when you need to reproduce the failure during testing.

Common Symptoms of P0079

Check Engine light is illuminated on the dashboard
The affected exhaust valve control system operates intermittently or stops functioning entirely
Engine may enter limp mode, limiting power and revs to protect components
Fuel consumption may rise noticeably in some vehicles
Reduced engine performance or sluggish acceleration under certain conditions
In rare cases, rough idling or minor stumbling at low engine speeds

What Causes P0079

An open circuit or a short-to-ground somewhere in the exhaust valve control solenoid wiring
Corroded, loose, or physically damaged connector terminals in the circuit
A failed exhaust valve control solenoid, actuator, or associated sensor
Poor or interrupted ground connection at the solenoid or control module
Chafed wiring insulation allowing unintended contact with ground or other circuits

How to Diagnose P0079

Plug in an OBD2 scanner and confirm that P0079 is the active or stored code. Save the freeze frame data immediately — it shows engine load, RPM, coolant temperature, and vehicle speed at the moment the fault triggered, which helps you recreate the failure condition during testing.
Pull any related trouble codes as well. Codes that appear alongside P0079 often point to the underlying cause, such as a failing sensor or a short in the wiring harness.
Check manufacturer technical service bulletins (TSB) for your make, model, and model year. Search by VIN on the automaker's website or through nhtsa.gov — many P0xxx codes have published factory fixes, software updates, or known issues that speed up diagnosis.
Visually inspect the wiring harness and connectors for the exhaust valve control solenoid circuit on Bank 1. Look for broken insulation, corrosion buildup, bent pins, loose plugs, or any sign of moisture intrusion.
With the connector unplugged, measure reference voltage, ground integrity, and signal continuity at the solenoid side of the harness. Compare your readings to the specifications in the service manual.
Perform a wiggle test on the harness while monitoring live data on the scanner. Any signal dropout or fluctuation points to a broken wire or intermittent connector fault. After repairs, clear the code, complete a full drive cycle that recreates the freeze-frame conditions, and verify that P0079 does not return.

Repair Options for P0079

Wiring or connector repair: $80–$250. Fixing frayed wires, replacing damaged terminals, or sealing a corroded connector is almost always the first line of attack and the least expensive.
Replace the faulty solenoid or actuator: $150–$500. If testing confirms the component itself is receiving proper voltage and ground but still fails to operate, replacement is necessary.
Control module repair or replacement: $300–$1,000. In rare cases the ECM or a related control unit is at fault, which drives up cost significantly.

Total Cost to Fix P0079

The final bill hinges entirely on what part of the circuit actually failed. Parts and labor for a typical independent shop repair break down as follows: wiring or connector repair runs $80–$250, a new solenoid or actuator typically costs $150–$500 installed, and control module diagnosis or replacement ranges from $300–$1,000. Most vehicles fall well below the highest estimate. The most important step is confirming the root cause before purchasing parts — a $50 connector repair solves many P0079 cases, so do not assume an expensive fix is needed right away.

Can You Drive with P0079?

In most situations, the vehicle remains driveable after P0079 sets. You may notice slightly reduced performance, higher fuel usage, or a mild limp-mode condition depending on which solenoid or system is affected. If the engine stalls, fails to start, or you see brake or power-steering warnings alongside the code, treat it as a priority and have it diagnosed immediately. Otherwise, schedule service at your earliest convenience — the problem will not resolve on its own, and continued operation with a faulty exhaust valve control circuit can compound wear on other engine components over time.