Error Code P0240 is defined as Turbocharger Boost Sensor B Circuit Range/Performance. This code is set when the boost pressure signal goes higher than the predicted range.

It’s a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, especially vehicles made since 1996 up to present. Specifications on the definition, troubleshooting and repair of course, vary from one make or model of vehicle to another.


Error Code P0240 is set when the PCM (powertrain control module, also known as ECM or engine control module in other makes of vehicle) detects that the intake boost pressure sensor B input circuit range performance is out of its predetermined specifications when compared to MAP (manifold pressure sensor) or BARO (barometric pressure sensor) when the vehicle is at idle and with the key turned on, engine off, before the start of the engine.

Common Symptoms

As with other error codes, Error Code P0240 causes the PCM to activate the Check Engine light. Other common symptoms include:

  • PCM turns the turbo boost off, causing lack of power to the engine
  • Failing boost sensor causes the sensor to register incorrect amount of boost pressure, resulting in a lack of power on acceleration

Possible Causes

This trouble code happens when the pressure sensor B doesn’t associate the same voltage input to the PCM with MAP or BARO sensor at engine idle or at key on, engine off. Other possible causes include:

  • Contaminated or clogged turbo boost pressure sensor B (clogged with carbon or debris deposits)
  • Turbo boost pressure sensor B responds slowly in changing pressure, a case caused by deterioration with age

How to Check

As with other error codes, technicians troubleshoot this error code by scanning and documenting the freeze frame data to verify the problem.

Next, they clear the codes to see if it comes back.

Then, they check the boost pressure’s operation and compare it with the MAP sensor.

Next, they look for any signs of blockage in the sensor port, boost sensor line or hose.

Then, they look for any signs of corrosion or damage in the pins of the turbo boost sensor connector.

Next, they check the pressure sensor lines and check for signs of damages or kinks.

How to Fix

Fixing Error Code P0240 is quite straightforward, and most cases can be resolved by simply replacing the boost sensor that doesn’t provide the PCM with the right input pressure.

Blockage of the links or kinks in the connections to the turbo boost sensor, hoses or connections must be repaired, if not replaced.

This error code is also referred by technicians as ‘detonation’ or ‘spark knock’. It’s a type of combustion that causes buildup of too much heat and pressure inside the combustion chamber of the engine. When this happens, we usually hear pinging noise or metallic knocking. A minor case of detonation don’t usually cause major problem. However, heavy and prolonged knocking can cause serious damage; it can crush rod bearings, punch holes in the pistons, crack rings, blow out head gaskets, or even pound out piston ring grooves. This is why prolonged pinging noise, which is a result of this error code, is a definite concern.

If the turbo boost pressure sensor is having problem, such as out of specified range, the PCM will automatically disable the engine’s turbo boost, rendering lack of power on acceleration, and causing various engine performance problems.