Powertrain, generic · Auxiliary emission controls

P048B Exhaust Pressure Control Valve A Position Sensor/Switch Circuit

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. P048B is the general circuit fault or open circuit of valve A's position sensor or end switch. VW's 2.0 TDI of 2009–13 sets it with a corroded flap; on the 2015 engine it appears with P048E, P0475, P0477 and P0478 and the actuator with its integrated electronics is replaced; Bentley's V8 of 2023 reports it for bank 1 together with P048D. As the sensor sits in the actuator, a circuit fault often means actuator electronics.

Likely causes

Actuator with integrated position sensor faulty

Connector or wire at the underbody corroded, chafed or open

Engine module (sensor supply or input)

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€150–900

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

P048C P048D P048E P048F P0475 P04A6

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.