What it means
The boost pressure sensor A 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 A reports pressure in the forced-induction system to the engine control module. P025E sets when Sensor A's signal drops out or fluctuates erratically, so the module cannot rely on its boost reading.
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 A alongside engine load and boost data to identify when its signal becomes erratic.
- Inspect Sensor A's connector for looseness or corrosion and check the harness for vibration, rubbing, or damaged insulation.
- With the engine running only under safe conditions, gently move the sensor harness while watching the signal for dropouts.
- Check Sensor A's power, ground, and signal circuit using the manufacturer's wiring diagram and compare readings with its specification.
- If the wiring remains stable, inspect the sensor mounting and test or replace Boost Sensor A as directed by the manufacturer.
Common fixes
- Secure the loose Sensor A connector and restore its seal if damaged.
- Clean or repair corroded connector terminals.
- Reroute or secure the harness away from vibrating or rubbing parts.
- Replace Boost Sensor A if its signal remains intermittent with sound wiring and mounting.
Can I keep driving?
Power loss or limp operation can make acceleration unreliable; avoid hard acceleration and towing until the signal is stable. If smoke, a strong hiss, or severe power loss occurs, stop driving and have the boost system checked.
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.