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Rock Sam

Rock Sam 8/14/2018

2008 Hummer H3 Base 5 Cyl 3.70L


How do I diagnose P0046 OBD-II Trouble Code of my car and what are its causes? What causes turbo Charger Boost

1 Answer

PartsAvatar Ca

PartsAvatar Ca 8/14/2018

What the P0046 code means?

This code has varied definitions as provided by the manufacturer. Generally, the Engine Control Unit (ECU) has detected an out of range reading in the turbocharger or supercharger boost control circuit. This code is related to circuit A and an area of the system circuit, as opposed to a particular malfunction or component.

What causes the P0046 code?

• Faulty boost pressure/ turbocharger position sensor

• Failed turbocharger/super charger

• Defective control solenoid

• Wiring problems

• Faulty PCM Vacuum leaks if the valve is vacuum controlled

What are some of the symptoms of P0046 code?

Symptoms may include reduced engine acceleration, whining or rattling noises from the turbocharger or turbo pipes, abnormal smoke from the exhaust, spark plug fouling, excessive engine or transmission temperature, hissing noises from the turbocharger wastegate and/or hoses, and an overall lack of engine performance. Additional codes may include other boost codes, engine misfire codes, or knock sensor codes. Cylinder detonation is another possibility, due to high engine temperatures. The boost pressure gauge (if so equipped) will exhibit abnormal levels of boost pressure.

Common mistakes when diagnosing the P0046 code:

Technicians report that failure to flush all debris and obstructions from the turbocharger oiling system can lead to repeated turbo failure. Turbocharger replacement without exhaustive testing of wastegate function and electrical circuitry is also the cause of frequent mishaps.

What repairs can fix the P0046 code?

This code indicates that the operation range and performance is not being achieved, but it has many potential causes for the general problem, so the mechanic will have to do many tests in order to find the true cause and path to repair, before repairing or replacing any components, or assuming that the issue is solely due to a vacuum or oil leak, or bad wiring or connectors. If the vehicle has been running erratically and the boost gauge operates in coordination with the running conditions, then the mechanic should check closely for obvious leaks on the intake system after the turbo such as hoses, clamps, the intercooler and piping, when the vehicle is just sitting off or at idle. The problem may not be obvious as it usually happens when the engine is under load.


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