P2566 – Turbocharger (TC) boost control position sensor – circuit intermittent

Reinier

By Reinier (Contact Me)
Last Updated 2022-03-29
Automobile Repair Shop Owner

CodeFault LocationProbable Cause
P2566 Turbocharger (TC) boost control position sensor - circuit intermittent
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Wiring, poor connection, TC boost control position sensor

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What Does Code P2566 Mean?

OBD II fault code P2566 is a generic trouble code that is defined as, “Turbocharger (TC) boost control position sensor – circuit intermittent”, or sometimes as “Turbocharger Boost Control Position Sensor “A” Circuit Intermittent”, and is set when the PCM (Powertrain Control Module) detects an intermittent failure in the control and/or signal circuit(s) of the turbocharger’s boost control valve’s position sensor.

NOTE: The presence of code P2566 indicates an intermittent problem in either the electrical control circuit of the turbocharger boost control position sensor or the position sensor itself and rarely (if ever) involves malfunctions of the turbocharger itself.

In terms of operation, the turbo boost control sensor converts the turbo chargers’ boost pressure into an electrical signal, which signal the PCM uses to calculate appropriate fuel delivery and ignition timing strategies based on the boost pressure being developed. In practice, the PCM uses this signal to “fine-tune” the level of boost pressure that is required by the engine at any given moment. Thus, the function of the turbo boost control sensor is to prevent over boost conditions that can seriously damage the engine, as well as under boost conditions that have serious negative effects on engine power.

Note that the operation of the turbocharger is independent of the turbo boost control sensor. If the turbocharger is in a good condition and operating as designed, a fully functional turbo boost control sensor will merely convert the boost pressure being developed into an electrical signal to alert the PCM that the maximum allowable boost pressure had been reached, or that insufficient boost pressure is being developed.

In the former case, the PCM will open a dumping mechanism to reduce the turbo chargers’ rotational speed to reduce boost, or if the boost pressure is insufficient to suit current operating conditions, close the mechanism to increase the turbo chargers’ rotational speed, thereby increasing boost pressure.

However, for the boost control system to work as intended the PCM has to “know” whether (or not, as the case may be), the mechanism that controls the actual boost pressure is functional. This mechanism goes by many names, including “wastegate”, “dump valve”, and others, but in all cases, this mechanism is fitted with a position sensor whose function is to relay the position of the mechanism to the PCM.

Regardless of whether the dumping mechanism is operated by the engine vacuum or by an electrical actuator, the position sensor will indicate (to the PCM) if the dumping mechanism is in the open or closed position. However, it should be noted that on variable geometry turbochargers, the position sensor will indicate the position of the variable vanes on the rotating assembly.

In practice, variable geometry turbochargers regulate the boost pressure they develop by varying either the position or angle of the vanes on the turbine wheel, so in these designs, the function of the boost control position sensor is critical to the correct operation of the turbocharger.

Regardless of the turbo chargers’ design, though, the PCM has to be able to exert precise control over the actual boost pressure being developed to ensure that the engine performs at its peak at all times. As mentioned elsewhere, excessive boost pressure can damage the engine, while insufficient boost pressure reduces engine performance, so when the PCM detects an intermittent failure in the boost control valve’s position sensor, it will recognize that it cannot control the boost pressure effectively. When this happens, the PCM will set code P2566, and also illuminate a warning light because this failure has the potential to increase harmful exhaust emissions.

Where is the P2566 sensor located?

This image shows an example of a turbocharger wastegate actuator that is vacuum operated and which attaches directly to the turbocharger. In this example, the green arrow indicates the attachment point for the vacuum hose that controls the movement of the actuator, while the yellow arrow indicates the mechanical linkage between the actuator and the turbochargers’ dumping mechanism.

The large red circle indicates the position sensor that is built into the actuator. In this case, the electrical connector links the actuator/position sensor assembly to the larger boost control system, but note that while all designs follow this general pattern, both boost control actuators and position sensors are calibrated to be application-specific. Put differently, this means that these components are not interchangeable, even if any given part fits multiple applications.

What are the common causes of code P2566?

Common causes of code P2563 could include the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and or connectors
  • Defective turbocharger boost control position sensor
  • In rare cases, this code can be caused by restrictions in the inlet or exhaust system
  • Failed or failing PCM, but note that since this is a rare event, the fault must be sought elsewhere before any control module is replaced or reprogrammed

What are the symptoms of code P2566?

Common symptoms of code P2563 could include the following-

  • Stored trouble code and an illuminated warning light
  • Depending on both the application and the nature of the problem, multiple additional codes may be present along with P2566
  • Power loss that can vary from slight at certain engine speeds, to severe at all engine speeds
  • Fuel consumption may increase considerably
  • The engine may hesitate or stumble upon acceleration
  • In some cases, severe engine damage may result if the turbo boost pressure cannot be controlled effectively