P0079

Code

Generic P — Powertrain

Exhaust Valve Control Solenoid Circuit Low Bank 1

Brand: Generic

Type: P — Powertrain

Views: UK: 15 EN: 22 RU: 29

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Page language: EN

Open or shorted wiring in the solenoid circuit (short to ground or high resistance)
Poor or corroded connector at the solenoid or ECM
Failed exhaust valve control solenoid (coil open or internal fault)
Low battery or weak power supply to the circuit (fused feed issue)
Faulty ECM or driver transistor (less common)
Mechanical binding or seized exhaust valve preventing proper feedback (if feedback sensor used)

MIL/Check Engine Light illuminated
Reduced engine performance or limp mode on some vehicles
Unusual exhaust drone or abnormal exhaust note (exhaust flap not operating)
Failed emissions test
Possible rough idle or hesitation if the exhaust system behavior affects drivability

Read freeze frame and live data with a scan tool; note when code set (cold start, warm, throttle state)
Visually inspect solenoid connector and wiring for damage, corrosion, exposed wires, pin push-out
Check fuses and power feeds related to exhaust valve solenoid
Measure supply voltage at the solenoid connector with ignition ON (key on, engine off)
Measure resistance of the solenoid coil (unplugged) and compare to specification
Back-probe control pin while commanding solenoid on/off with a scan tool to confirm PWM/duty or switched ground

Control signal: typically a switched ground or PWM from ECM; expected to toggle when commanded
Supply voltage: battery voltage (~11.5–14.5 V) at solenoid power pin with ignition ON
Control voltage when inactive: near battery voltage (open) or 0 V if driver grounds when off depending on design
Control voltage when active: pulled to ground or pulsed by ECM (measure PWM duty and frequency with scope or graphing scan tool)
Typical coil resistance: commonly in the range 5–30 ohms (manufacturer-specific), open circuit indicates failed solenoid
Typical current draw: often 0.1–2 A depending on solenoid; excessive draw indicates short or mechanical bind

Retrieve freeze frame, history, and related codes. Confirm code is Bank 1 exhaust valve control solenoid circuit low (P0079).
Perform a careful visual inspection of wiring and connectors from the ECM to the exhaust valve solenoid (Bank 1). Repair obvious damage.
With connector disconnected, measure coil resistance across the solenoid pins. If infinite or out-of-spec, replace solenoid.
With connector connected, measure battery feed pin for constant battery voltage with ignition ON. If missing, check fuses, fusible links, and power feed circuits.
Back-probe the control pin. Command the solenoid ON and OFF with a scan tool while observing the control line. Verify the ECM is sending a switching/PWM or ground signal when commanded. If ECM does not command, suspect wiring or ECM programming.
Check for a short to ground on the control wire: with ignition OFF, measure resistance from control pin to chassis ground. Very low resistance indicates short.
If control signal is present but solenoid does not actuate, apply bench 12 V to the solenoid quickly (observe correct polarity and safety) to verify mechanical operation. Only do this when safe and appropriate.
If wiring and solenoid are good but control signal is absent or incorrect, test ECM driver output per manufacturer procedure. Replace ECM only after other faults excluded.
Clear codes and test drive to verify repair. Monitor for recurrence and check related DTCs.

⚠️ Status

Exhaust Valve Control Solenoid Circuit Low - Bank 1: Low/No control signal detected on exhaust valve solenoid circuit for Bank 1.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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