What it means
Exhaust pressure sensor B reads in range but plausibility check fails. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
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 reports exhaust pressure for DPF or turbo control, depending on the vehicle. The control module sets P047B when sensor B’s reading is within its electrical range but does not behave plausibly for the engine’s operating conditions.
Common causes
Most likely first.
- Sensor drift
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Check-engine light on
- Possible reduced engine power or sluggish acceleration
- Possible increased exhaust smoke
- Possible reduced fuel economy
How to diagnose it
- Save freeze-frame data and compare sensor B live readings with engine speed and load to identify the conditions that make the reading implausible.
- Inspect sensor B’s mounting and pressure connection for looseness, leakage, blockage, or damage that could damp or distort pressure changes.
- Check sensor B’s wiring and connector for chafing, water ingress, pin push-back, or poor contact.
- With live data displayed, gently move the sensor B harness to see whether the reading changes unexpectedly.
- Compare sensor B’s response with the manufacturer’s specification and verify the pressure passage before replacing the sensor.
Common fixes
- Secure a loose sensor B mounting or pressure connection.
- Repair damaged wiring or connector terminals affecting sensor B.
- Clear or repair a restricted or leaking pressure passage.
- Replace sensor B if its reading remains implausible after the mounting and circuit checks.
Can I keep driving?
Use moderate throttle and avoid towing until the pressure reading is trustworthy. Continued implausible data can impair DPF or turbo control, increase smoke, or cause reduced power.
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.