P2564 OBD-II Trouble Code: Turbocharger Boost Control Position Sensor Circuit Low

P2564 trouble code definition

A P2564 trouble code indicates an abnormal reading in the turbocharger’s boost control position sensor circuit. The sensors’ input voltage signals, as sent to the PCM, are showing a boost level that is higher or lower than the manufacturer’s specs.

What a P2564 code means

Most turbochargers run between 9 to 14 pounds of boost, and a P2564 code means that the boost levels are higher or lower than these normal parameters. The PCM then stores a trouble code that reads as a problem in managing normal boost levels.

Symptoms of a P2564 code

Symptoms of a P2564 code can include:

• Lack of power and poor acceleration
• Spark plug fouling
• Cylinder detonation
• Excessive smoke from the exhaust
• High engine or transmission temperatures
• Hissing sounds from turbo wastegate and/or hoses
• Whining, hissing or rattling noises from the turbo unit or turbo pipes and plumbing
• High or low levels of boost on boost pressure gauge (if so equipped)

Boost codes, engine misfire codes and knock sensor codes may accompany the P2564 code.

Causes of P2564 code

• Clogged, dirty air filter
• Vacuum leak at intake manifold
• Wastegate stuck either open or closed
• Failed intercooler
• Failed boost sensor
• Turbo failure
• Shorted or open wiring in boost sensor circuitry
• Loose bolts at exhaust manifold/turbocharger connections
• Loose flange between turbocharger and intake pipe
• Corrosion or disconnected electrical connectors at boost sensor’s 5-volt reference circuit connection

Note that complete turbo failure can be due to internal oil leaks or restrictions in supply, which can result in:

• Cracked turbo housing
• Failed turbo bearings
• Damaged or missing blade on impeller itself
• Bearing wobble, which can cause the impeller to rub on the housing, destroying the unit

Diagnosing the P2564 Code

Remember that a turbocharger is essentially an air compressor, forcing air into the engine’s fuel system via impellers that are driven by exhaust gas pressure. There are two separate impellers in two chambers, with one driven by exhaust pressure and, in turn, spinning the other impeller. The second impeller brings in fresh air through the turbocharger intake and intercoolers, supplying cooler, denser air into the engine. Cooler, denser air helps the engine build horsepower by running more efficiently; as the engine’s RPMs climb, the forced air system spins faster, and at about 1700-2500 rpms, the turbo begins to spool up and deliver peak air flow to the engine. The turbo runs extremely hot and at extremely high RPMs, in order to produce air pressure that’s several times that of the atmosphere.

Each manufacturer designs their turbochargers with maximum boost specifications, which are then programmed into the PCM. Boost range is calculated to avoid engine failure due to excessive boost, or poor performance due to low boost pressure. When the boost levels are out of these parameters, a code is stored in the PCM and the malfunction indicator lamp (MIL) will illuminate.

• Have an OBD-II scanner, boost pressure gauge, hand-held vacuum pump, vacuum gauge and dial indicator set on hand.

• Test drive the vehicle and listen for misfires or engine knocks

• Inspect all turbo hose amps for tightness, and inspect turbo intake and intercooler connections for leaks or cracks.

• Inspect all air intake hoses for condition and tightness.

• If all hoses, plumbing and connectors seem good, firmly grasp the turbo and try to move it on the intake flange. If the housing can be moved at all, tighten all bolts and nuts to manufacturer’s torque specs.

• Place a boost gauge so that you can see it while actuating the throttle.

• Start the vehicle in Park and quickly rev the engine to 5,000 rpms or so, releasing the throttle quickly. Observe the boost gauge and see if it exceeds 19 pounds – if so, suspect a stuck wastegate.

• If boost is low (14 pounds or less), suspect a turbo or exhaust problem. You’ll need your code reader, digital volt/ohmmeter and manufacturer’s wiring diagram.

• Do a visual inspection of all wiring and connectors, and replace any damaged, disconnected, shorted or corroded parts as needed. Retest the system.

• If all wiring and connectors (including fuses and components) seem OK, connect the code reader or scanner to the diagnostic port. Record any codes and freeze frame data. Clear codes and test drive the vehicle. If codes fail to return, you may have an intermittent condition. Wastegate Malfunction

• Disconnect the actuator arm from the wastegate assembly itself.

• Use the vacuum pump to manually engage the actuator valve. Watch the wastegate to see if it can fully open and close. If the wastegate can’t fully close, it will cause a dramatic drop in boost pressure. A condition where the wastegate can’t open fully will cause a drop in boost pressure as well.

Turbocharger Malfunction

• With the engine cool, remove the turbo outlet hose and look inside the unit.

• Inspect the unit for impeller fins that have been damaged or are missing, and look for signs that the impeller blades have been rubbing the inside of the housing.

• Look for oil inside the housing

• Spin the blades by hand, and listen and feel for loose or noisy bearings. Any of these conditions can indicate a failed turbocharger.

• Install the dial indicator on the turbine outlet shaft and measure lash and endplay. Anything outside of .003 is considered excessive endplay.

• If you find no problems with the turbo and wastegate, locate a constant supply of vacuum at the intake manifold and connect a vacuum gauge.

• With the engine at idle, an engine in good working order should read between 16 and 22 inches of vacuum. Anything less than 16 inches of vacuum can possibly point to a bad catalytic converter.

• If no other obvious problems have presented themselves, re-test the circuits, wiring and connectors of the turbocharger’s boost sensor.

• Check voltage and resistance values against manufacturer’s specs, and repair/replace as necessary.

Need help with a P2564 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.