What it means
A general electrical fault on exhaust pressure sensor B — used to monitor backpressure across the DPF or to control variable-geometry turbo.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Exhaust pressure sensor B measures exhaust pressure for systems such as DPF monitoring or turbo control, depending on the vehicle. The control module monitors sensor B’s electrical circuit and sets P047A when it detects a general circuit fault rather than a specific high, low, or plausibility condition.
Common causes
Most likely first.
- Exhaust pressure sensor B failure
- Open or short in sensor wiring
- Corroded or loose connector
- Blocked or damaged pressure passage
Symptoms
- Check-engine light on
- Possible reduced engine power
- Possible increased exhaust smoke
- Possible reduced fuel economy
How to diagnose it
- Record freeze-frame data and compare live sensor B readings with engine speed and operating conditions to see when the circuit fault appears.
- Inspect sensor B’s connector, wiring, and pressure passage for corrosion, looseness, damage, blockage, or heat exposure.
- Check the sensor B circuit for opens or shorts using the wiring diagram and manufacturer’s test procedure.
- Verify that the pressure passage is clear and that the sensor is receiving the pressure it is intended to measure.
- Test sensor B against the manufacturer’s specification and replace it only if the circuit and passage are sound.
Common fixes
- Reconnect or clean sensor B’s loose or corroded connector.
- Repair open or shorted wiring in the sensor B circuit.
- Clear a blocked pressure passage or replace a damaged passage connection.
- Replace exhaust pressure sensor B if its output fails the specified test.
Can I keep driving?
A short, gentle drive may be possible if power and exhaust behavior remain normal, but avoid towing or heavy acceleration. Incorrect pressure readings can affect turbo or DPF control and may lead to reduced power or worsening smoke.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.