P0048 Code- Turbocharger/Supercharger Boost Control 'A' Circuit High

What Does Code P0048 Mean

This code has varied definitions as provided by the manufacturer. The code means that the ECU (Engine Control Unit) has detected an out of range or abnormal reading of too high operation in the turbocharger or supercharger boost control solenoid circuit. This code is related to the electrical circuit A as an area of the boost solenoid system circuit, as opposed to a particular malfunction or component.

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Possible symptoms

• Engine Light ON (or Service Engine Soon Warning Light)

What causes the P0048 code?

• Vacuum system leak on the intake manifold or boost control
• A defective air cleaner
• The waste gate is stuck closed
• Loose connection or bad gasket between the exhaust manifold and the turbocharger flange
• A restrictive connection between the turbocharger and the air intake connection
• A bad boost pressure sensor
• Shorted or open wiring in the boost sensor circuit
• Loose, corroded, or disconnected electrical connectors in the boost sensor 5-volt reference circuit
• Damaged turbo charger (usually caused by internal oil leaks and oil supply problems which can lead to bearing failure and blade damage)

Troubleshooting P0048

If the PCM detects a turbocharger/supercharger boost control solenoid circuit voltage signal that is high or detects an actual boost pressure condition (under programmed conditions), a P0048 will be stored and a service/check engine soon lamp may be illuminated.

I would begin my diagnosis with a careful visual inspection of all related wiring, connectors, components, and vacuum hoses. Repair or replace damaged, burnt, or disconnected parts as required. Also, check battery cable and battery post condition. Carefully rectify loose or corroded battery connectors and/or terminals before proceeding with your diagnosis.

Continue by noting all stored codes and freeze frame data before clearing all codes from the system. Clearing the codes may allow the turbocharger/supercharger boost control system to return to normal operating conditions if the PCM placed it in a failure or “limp-in” mode. It may also make you aware of an intermittent failure condition that will be much more difficult to diagnose than a “hard” failure.

After the codes have been cleared, obtain a manufacturer’s service manual (or equivilant) with a diagnostic flow chart for this code. You may carefully follw the steps of the flow chart but here a few basic tests that you may attempt:

Boost Control Solenoid

After obtaining specifications for the boost control solenoid, disconnect the solenoid electrical connector and use a digital volt/ohmmeter (DVOM) to check solenoid resistance levels. If solenoid resistance fails to comply with specs, replace it and retest the system. If solenoid resistance complies with the specs in the service manual, carefully apply battery voltage and a ground signal to the solenoid and listen for an audible “tick”. If the solenoid makes a sound, it is likely functioning properly. Check the passages of the solenoid for signs of obstruction and replace as necessary.

System Circuitry

If system wiring and connectors appear to be in proper working order, perform a circuit voltage and continuity test.

Test voltage at the boost control solenoid when it is commanded ON and compare your actual findings with manufacturer’s specifications. If the signal fails to comply, establish which of the signals (voltage or ground) are absent according to your particular vehicle specifications.

Prior to testing for individual system circuit continuity, disconnect the connector from the PCM and all related components to prevent possible damage. Use the DVOM to test continuity on each individual circuit and repair open (disconnected, cut, burnt, or disconnected) circuits and shorted (to ground or vehicle voltage) circuits as required.

PCM

While testing the PCM is not feesible, you may follow a process of elimination and remember that failure of this component is rare.

Searches related to P0048

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