P0479 Exhaust Pressure Control Valve A Intermittent

The exhaust pressure control valve is a flap in the exhaust: on older Navistar/Ford diesels a warm-up flap that raises back pressure when cold, on Ram and others an exhaust brake, on VW's 2.0 TDI a flap that drives the low-pressure EGR, and on Audi and Bentley a sound flap. P0479 means an intermittent circuit or function fault of valve A. No manufacturer document available to us uses this code; Audi describes its flap faults as mostly sporadic under P0475/P0477, and Bentley distinguishes intermittent from static faults in the fault memory. Typical causes are a loose contact or commutator wear in the flap motor. CARB requires output components to be monitored.

Likely causes

Symptoms

• Check engine light on, possibly only after several events
• Occasional flap noise or malfunction

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, static.nhtsa.gov, patents.google.com.