Fault codeP0240

SEVERE

Turbocharger Boost Sensor B Circuit Range/Performance

What this code means

Turbocharger Boost Sensor B Circuit Range/Performance.

P0240 is a generic code: it means the same thing on every make. P0240 belongs to family P02xx — Injector circuit. Its page explains how to read a code and groups all its codes by part.

Type of fault

The signal stays within its electrical limits, but its value is not plausible: it does not match what the control unit expects given the other sensors. The sensor may be drifting with age, but it may also be faithfully measuring a real mechanical problem — a leak, a blockage, an air leak. Replacing the sensor without checking does not always clear the fault.

Boost pressure sensor

This sensor measures the pressure of the air the turbo pushes into the intake. The control unit uses it to regulate boost: it opens or closes the wastegate or the variable vanes to reach the pressure it wants.

What you notice

Usually a sharp loss of power, the engine switching to limp mode to protect the turbo; sometimes jerks under acceleration.

How to check it

Check its connector and wiring, then the sensor's port: oil vapour from the crankcase ventilation can clog it. Ignition off, the sensor should read about the same as the atmospheric pressure; Klaro shows both values side by side for that comparison.

Watch it live in Klaro

With an OBD2 adapter plugged in, these live readings show the part at work, when your car reports them:

Intake manifold pressure
Barometric pressure

What to do

Have it checked promptly. An injection, fuel-supply or boost fault can cost power, cause misfires and eventually damage the engine or the catalytic converter. If the light is flashing or the engine is overheating, stop driving.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →

How to read this code

PPowertrain
0standardised code
2Injector circuit
40P0240