P0049 OBD-II Trouble Code: Turbo/Super Charger Boost Control Solenoid Circuit/Open

P0049 code definition

Turbo/Super Charger Turbine Overspeed

What the P0049 code means

This code has varied definitions, depending on the manufacturer. The code is generated when the Engine Control Unit (ECU) detects an abnormal reading in the turbocharger or supercharger overspeed sensor circuit.

What causes the P0049 code?

Generally, the P0049 code is related to the circuit and sensor on the turbo/super charger which determines the actual speed of the unit. The fault indicates that the turbo/super charger is turning too fast, which is not a common situation, so the cause is usually related to the wiring or speed/boost sensor. Also, the boost control valve or waste gate may be stuck shut.

What are some of the symptoms of P0049 code?

• Over-boost condition, or no boost condition, depending on the failure
• Engine acceleration: no power or excessive power (can lead to engine damage)
• Check Engine Light illumination once ECU detects overspeed condition.

How does a mechanic diagnose the P0049 code?

• Checks for the engine warning light to illuminate on the dash
• Uses an OBD-II scanner to determine the code
• Resets the code and tests the vehicle to see if the code returns

If the P0049 code returns, the mechanic should follow these test procedures:

• Inspect the turbo/super charger system, especially for the solenoid valve and wastegate being inoperative or stuck

• Inspect the wiring on the boost sensor/speed sensor and related wiring for loose connections, damaged wiring, or a faulty sensor

• Check the boost pressure during operation and driving for a normal range of 9 to 14 PSI pressure to insure it is not too high

• Inspect the turbo charger to ensure no damage or part failures

Common mistakes when diagnosing the P0049 code

Do not replace any component, assuming it is bad, without inspecting the system. The actual tested boost pressure is the best place to start to prevent common misdiagnosis.

How serious is the P0049 code?

This code is very serious and is usually preceded by the engine warning light coming on. It can accompanied by unusual engine noises including high pitched, rattling, hissing or unusual sounds. It should be diagnosed as soon as possible to prevent engine internal damage, or turbocharger failure. The vehicle can run very erratically, backfire, have rich or lean fuel consumption problems, and operate in over boost conditions.

Minimize your driving until the problem can be repaired. If the vehicle operates very poorly, do not drive it further.

Often times, if the engine warning light comes on immediately at start up, the OBD- II system can be reset and the vehicle will operate normally.

What repairs can fix the P0049 code?

Finding the best path to repair for the P0049 code is often confusing, and the notion of turbo/super charger overspeed can have many associated problems that are the cause. Overspeed of the turbo/supercharger is actually rare and is more accurately described as an "over boost situation". It is quite possible that, if the bypass valve or wastegate is stuck closed, an overspeed or over boost condition can exist under full load conditions.

Often, an overspeed situation can be repaired by addressing a sensor or wiring issue. Older vehicles with more miles on them tend to have failing sensors, causing false output signals to the ECU.

Additional comments for consideration regarding the P0049 code

Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up or prolonged stress situations on the drive train. If the engine warning light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset using the scanner and the problem may not reoccur. This is why it is important to verify the fault and reset it before doing any repairs.

Need help with a P0049 code?

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