P0046 code definition
Turbo/Super Charger Boost Control Solenoid Circuit Range/Performance
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?
Vacuum leaks on the intake manifold
A dirty, restrictive air cleaner
The waste gate is either stuck open or closed
A plugged or leaking intercooler
Loose connections or a bad gasket between the exhaust manifold and the turbocharger
Loose connection between the turbocharger and the inlet pipe
A bad boost sensor
Shorted or open wiring in the boost sensor circuit
Loose, corroded, or disconnected electrical connectors in the boost sensor's 5-volt reference circuit
Turbo failure from internal oil leaks and oil supply problems, causing bearing failure and blade damage
What are some of the symptoms of P0046 code?
Low or no boost and a loss of power during acceleration (most common)
Engine boost will be zero and the engine will have no boost
The engine will idle normal; only acceleration will be affected
The Check Engine Light would then come on once the ECM has seen that the solenoid circuit has gone out of specifications
How does a mechanic diagnose the P0046 code?
The code is normally preceded by the Check Engine Light coming on the dash. The mechanic must use an OBD-II scanner to identify the code, then reset the code and test the vehicle to see if the code returns.
If the P0046 code returns, then the mechanic should follow the test procedure:
Inspect the turbo or super charger system for loose connections, including hoses and lines being cracked or damaged.
Inspect the wiring on the boost sensor and related wiring for loose connections, damaged wiring, or faulty sensor.
Check the boost pressure during operation and driving for normal range of 9 to 14 PSI pressure and ensure it is not erratic.
Inspect the turbo charger for damaged blades, wobbly shaft rotation, worn bearings, oil leaks into turbo boost side, and correct control valve or waste gate operation.
Common mistakes when diagnosing the P0046 code
Components should not be assumed to be bad and replaced without carefully inspecting the system first.
Some mechanics have reported that failure to flush all debris and obstructions from the turbocharger oiling system can lead to repeated turbo failure.
Turbocharger replacement without complete testing of the by-pass valve or waste gate function and electrical circuitry is also the cause of common misdiagnosis.
How serious is the P0046 code?
This code is very serious. It is usually preceded by the engine warning light coming on, and it must be diagnosed as soon as possible to prevent engine internal damage. Minimize your driving until the problem can be repaired.
The vehicle can run roughly, backfire, have rich or lean fuel consumption, and operate in over or under boost conditions.
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 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.
I have seen a cracked hose going to a throttle body that was cracked on the bottom, where I could not see or feel it; the crack opened and closed depending on the load. As the boost pressure increased, then the crack would open like a bladder valve and release pressure, but it operated normally under light loads. This problem can be elusive but does require perseverance to find it.
Additional comments for consideration regarding the P0046 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 P0046 code?
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This article originally appeared on YourMechanic.com as P0046 OBD-II Trouble Code: Turbo/Super Charger Boost Control Solenoid Circuit Range/Performance and was authored by John Nelson.