P0479 Code: Exhaust Pressure Control Valve A Intermittent
🟠 Moderate severity · drivable
Drivable, but the valve signal can drop in and out, causing rough running; fix it soon.
What P0479 means
The exhaust pressure control valve signal is cutting in and out instead of staying steady, so the engine computer cannot reliably control exhaust backpressure. Intermittent faults are usually caused by loose connectors, damaged wiring, or a valve that sticks occasionally. The engine may run fine sometimes and poorly at other times.
Symptoms
- Check engine light is on
- Intermittent rough idle
- Occasional loss of power
- Check engine light flickering on and off
Common causes
- most common: Loose or corroded valve connector
- common: Damaged or frayed wiring
- common: Valve sticking intermittently from carbon
- less common: Faulty valve actuator or sensor
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Clean and tighten the valve connector | Yes | $0–50 |
| Repair damaged valve wiring | Yes | $50–200 |
| Clean or replace the sticking valve | Mechanic | $150–400 |
Frequently asked questions
Can I drive with a P0479 code?
Yes, but the engine may run rough off and on. Fix the connection or wiring before it leaves you stranded.
Why does an intermittent valve code come and go?
The signal only fails sometimes, usually because a connector is loose or wiring is damaged and loses contact under vibration.
How much does it cost to fix a P0479?
Fixing a connection can be nearly free. Wiring repairs run $50–$200, and replacing the valve costs $150–$400.
Related codes
P0475
P0475 Code: Exhaust Pressure Control Valve A Malfunction
P0476P0476 Code: Exhaust Pressure Control Valve A Range/Performance
P0478P0478 Code: Exhaust Pressure Control Valve A High
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.