BOOSTSensor

Boost Pressure Sensor

Group: Air and fuel

The boost pressure sensor measures the pressure the turbocharger builds in the intake. The computer uses it to control the turbo and to limit pressure if it goes above target.

Contents

What does the BOOST sensor do?

It works like a MAP sensor with an extended range (up to 2.5 or 3 bar absolute). The computer compares the desired pressure with the actual one and moves the wastegate or the vanes of a variable-geometry turbo to reach it. If the pressure falls short it logs underboost (P0299); if it is too high, overboost (P0234), and it cuts power.

Where is it located?

In the intake pipe after the intercooler, or in the intake manifold. It often includes a temperature sensor.

Signal type and reference values

  • 3 pressure wires (5 V, ground, signal) and sometimes 1 more for temperature.
  • Engine off: atmospheric pressure (about 100 kPa at sea level).
  • Full load: from 150 to over 250 kPa absolute, depending on the engine.

Values are a guide only: always check the manufacturer's data for your engine.

Symptoms of a bad BOOST sensor

  • Loss of power and limp mode.
  • Whistling or hissing in the intake (a leaking boost hose).
  • Black smoke on diesels.
  • Codes P0234, P0236, P0237, P0238 and P0299.

How to test the BOOST sensor step by step

  1. With the engine off, boost pressure must equal barometric pressure.
  2. On a road test, log desired and actual pressure: a big difference points to a leak, the turbo or its control, not necessarily the sensor.
  3. Check the intercooler hoses, the clamps and the intercooler itself.
  4. Check the wastegate or variable-geometry actuator (free movement, no carbon buildup).
  5. Check for 5 V and ground at the sensor connector.

Trouble codes related to the BOOST sensor

Frequently asked questions about the BOOST sensor

Does a P0299 mean the turbo is broken?
Not always. The most common causes are leaking boost hoses, a stuck variable-geometry actuator or a faulty turbo control valve.
Are the boost sensor and the MAP sensor the same thing?
On many turbo engines, yes: it is the same sensor with an extended range. Others have two: one in the manifold and one after the intercooler.

Updated September 25, 2026. Values are a guide only: always confirm them in the service manual for your engine.

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