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. P048D means valve A's position signal is below its permitted voltage window – the signal wire is shorted to ground or the sensor's 5 V supply is missing. Bentley's Continental and Flying Spur V8 of 2023 report it for bank 1 together with P048B; the bulletin advises checking wiring and contacts, otherwise replacing the actuator and carrying out the basic setting.
Medium severity. Can I keep driving?Drive as little as possible and gently. If the transmission slips or stays in one gear, go slowly to a repair shop or call for a tow truck.
Symptoms
- Check engine light on
- Flap without function, exhaust sound changed
- VW/Audi TDI: EGR fault P0401 possible
Most likely causes
- Signal wire shorted to ground (chafed at the underbody)
- Position sensor or actuator faulty internally
- 5 V sensor supply open or shorted
- Moisture or corrosion in the connector
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P048D means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 4: Emissions
- 8D: Specific fault in that system
Frequently asked questions
Can I keep driving with code P048D?
Drive as little as possible and gently. If the transmission slips or stays in one gear, go slowly to a repair shop or call for a tow truck.
What causes code P048D?
The most common causes are: signal wire shorted to ground (chafed at the underbody); position sensor or actuator faulty internally; 5 V sensor supply open or shorted.
Related codes
- P048BExhaust Pressure Control Valve A Position Sensor/Switch Circuit
- P048EExhaust Pressure Control Valve A Position Sensor/Switch Circuit High
- P048CExhaust Pressure Control Valve A Position Sensor/Switch Circuit Range/Performance
- P048FExhaust Pressure Control Valve A Position Sensor/Switch Circuit Intermittent/Erratic
- P04A8Exhaust Pressure Control Valve B Position Sensor/Switch Circuit Low
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.