What it means
The boost pressure sensor B signal is intermittent or erratic. A wiring, connector, or sensor fault may cause the signal to drop out or fluctuate.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Turbocharger or supercharger Boost Sensor B measures pressure in the forced-induction system and sends that reading to the engine control module. P025F sets when Sensor B's signal is intermittent or erratic, preventing the module from getting a dependable reading from that sensor.
Common causes
Most likely first.
- Connector loose or corroded
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
How to diagnose it
- Record freeze-frame data and graph Boost Sensor B data to identify when its signal drops out or jumps unexpectedly.
- Inspect Sensor B's connector and harness for looseness, corrosion, vibration damage, and contact with nearby components.
- Gently move Sensor B's harness while monitoring live data to check for a vibration-sensitive signal interruption.
- Test Sensor B's power, ground, and signal wiring against the manufacturer's diagram and specification.
- If the circuit is stable, check Sensor B's mounting and test the sensor according to the manufacturer's procedure.
Common fixes
- Reseat the Sensor B connector and repair its seal if needed.
- Clean or replace corroded terminals.
- Secure or reroute wiring away from vibration and abrasion.
- Replace Boost Sensor B if the signal remains erratic with verified wiring and mounting.
Can I keep driving?
Unreliable boost readings can bring power loss or limp operation, so avoid hard acceleration and heavy loads. Stop driving if power loss is severe or exhaust smoke or an intake hiss appears.
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.