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

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.

Symptoms

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

Most likely causes

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

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the fluid level and condition according to the manufacturer
2. Gently move the wiring with the engine running and watch whether the reading changes.
3. Check the transmission connector
4. Read the data with a transmission-compatible scanner
5. Measure the solenoid valve circuit
6. Leave opening the transmission to a specialized repair shop

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P048F means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 4: Emissions
• 8F: Specific fault in that system

Frequently asked questions

Can I keep driving with code P048F?

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 P048F?

The most common causes are: loose contact or corrosion at the actuator connector; wire broken by vibration or heat; position sensor worn.

Related codes

• P048BExhaust Pressure Control Valve A Position Sensor/Switch Circuit
• P048CExhaust Pressure Control Valve A Position Sensor/Switch Circuit Range/Performance
• P048DExhaust Pressure Control Valve A Position Sensor/Switch Circuit Low
• P048EExhaust Pressure Control Valve A Position Sensor/Switch Circuit High
• P04AAExhaust Pressure Control Valve B Position Sensor/Switch Circuit Intermittent/Erratic

Sources

• law.cornell.edu: 13 CCR 1968.2
• static.nhtsa.gov: MC 10237572 0001
• static.nhtsa.gov: MC 10122916 9999

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.