P0299

DTC P0299

DTC DESCRIPTOR

DTC P0299
Turbocharger Engine Underboost

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

CIRCUIT/SYSTEM DESCRIPTION
The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by turbocharger output, engine speed, accelerator pedal input, air temperature, and barometric pressure (BARO). A diaphragm within the MAP pressure sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The MAP pressure sensor wiring includes 3 circuits. The engine control module (ECM) supplies a regulated 5-volt reference circuit, a ground on a low reference circuit, and the MAP pressure sensor provides a signal voltage to the ECM , relative to pressure on the signal circuit. The ECM converts the signal voltage input to a pressure value. Under normal operation the lowest pressure that can exist in the intake manifold is equal to the BARO. This occurs when the vehicle is operated at idle or when the ignition is on while the engine is off. The highest manifold pressures occur when the turbocharger output is high. Manifold pressure can range from 58 kPa (8 psi) when pressures are low to more than 240 kPa (34 psi) when pressures are high, depending on the BARO. The MAP pressure sensor has a range of 33 kPa (4 psi) to 255 kPa (36 psi). The ECM monitors the MAP sensor, by comparing a calculated predicted value at a predetermined engine load and speed, to the actual input.

CONDITIONS FOR RUNNING THE DTC
- DTC P2564 or P2565 is not set.
- The engine speed is between 800-3,000 RPM.
- DTC P0299 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The measured MAP pressure is 39 kPa below the expected range for 10 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- If the condition is intermittent. Refer to Testing for Intermittent Conditions and Poor Connections and Inducing Intermittent Fault Conditions.
- A MAP sensor that is stuck at BARO, or is 40 kPa lower than desired while under boost, will cause this DTC to set. Use a scan tool and compare the MAP Sensor parameters to a known good vehicle. Operate both vehicles under various conditions.

SPECIAL TOOLS REQUIRED
J 46091 Charge Air Cooler Tester

CIRCUIT/SYSTEM VERIFICATION
1. If DTCs P003A, P0045, P0698, P0699, P2563, P2564 or P2565 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
2. Verify the integrity of the air induction and turbocharger pipes and hoses by inspecting for the following conditions:
- Any damaged components
- Loose or improper installation
- Wet or restricted air filter
- Exhaust leaks before the turbocharger
- Exhaust restrictions after the turbocharger
- Charge air cooler leaks, with a Special Tools

IMPORTANT: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

CIRCUIT/SYSTEM TESTING
1. With the engine running, use a scan tool to command the TC Vane Pos. Ctrl. Solenoid ON. Take a snapshot of the engine data while slowly increasing the engine speed to 2,200 RPM, and then back to idle. Plot the snapshot and verify that the MAP sensor parameter increases smoothly as the engine speed is increased and decreased smoothly as the engine speed is returned to idle.
- If the MAP parameter does not change smoothly or does not follow engine speed, replace the MAP sensor.
2. Test the turbocharger oil supply feed. Refer to Turbocharger Lack of Oil Supply.
3. Inspect the turbocharger oil supply tube for restrictions.
- If a restriction is found, clean or replace the oil supply tube as necessary.
4. Inspect the turbocharger for debris, worn impeller and turbine blades, or damage
- If a worn or damaged turbocharger vanes are found, replace the turbocharger assembly.

REPAIR INSTRUCTIONS

IMPORTANT:
- Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- If any service has been performed on the turbocharger or on the turbocharger components, a turbocharger relearn must be performed. Failure to perform the turbocharger learn procedure may cause this DTC to set. Refer to Turbocharger Learn Procedure.
- Manifold Absolute Pressure (MAP) Sensor Replacement
- Turbocharger Vane Position Sensor Replacement