Powertrain, generic · Auxiliary emission controls

P048F Exhaust Pressure Control Valve A Position Sensor/Switch Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

An exhaust pressure control valve is an electrically driven flap in the exhaust with a position sensor or end-position switch, usually inside the actuator. Valve A is the first such flap; Bentley's V8 assigns A to bank 1 and B to bank 2. Documented uses are the flap behind the particulate filter of VW's and Audi's 2.0 TDI, which raises back pressure for the low-pressure EGR, and the sound flaps of Audi and Bentley. P048F means valve A's position signal jumps, drops out briefly or changes faster than physically possible. Bentley stores sporadic sensor faults under the low code with a sporadic status instead. No manufacturer document available to us uses this code; the description follows the sibling codes P048B–P048E and CARB.

Likely causes

Loose contact or corrosion at the actuator connector
Wire broken by vibration or heat
Position sensor worn

Symptoms

  • Check engine light on
  • Flap without function, exhaust sound changed
  • VW/Audi TDI: EGR fault P0401 possible

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–2.5 h

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

Parts involved

exhaust pressure control valve a position sensorexhaust pressure control valve asensor wiringengine control module

Related codes

P048BP048CP048DP048EP04AA

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.