P0299
P0299-TURBOCHARGER UNDERBOOST CONDITION
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The base Turbocharger boost pressure is managed by the mechanical Wastegate. The Wastegate is a mechanical valve that, when opened, allows exhaust gases to flow around the turbine. The Wastegate is spring loaded in the closed position. Boost pressure is applied to a diaphragm that works against the spring pressure of the Wastegate. When the force created by the boost pressure exceeds the spring force in the Wastegate, the valve opens. This limits boost pressure by limiting the speed of the Turbocharger. Boost pressure is applied against the spring pressure of the Wastegate to control the speed of the Turbocharger. The Wastegate Solenoid is Pulse Width Modulated (PWM) by the PCM and is located between the compressor and mechanical Wastegate. When opened by the PCM, the Wastegate Solenoid bleeds boost pressure away from the mechanical wastegate, this allows the PCM to increase boost pressure to a level higher than would be allowed by the mechanical wastegate alone. The system operates as follows; boost pressure is supplied to the Wastegate Solenoid through a hose connected to the compressor side of the Turbocharger. The Powertrain Control Module (PCM) varies the PWM signal to the Wastegate Solenoid to control the amount of boost pressure applied against the Wastegate. When more boost pressure is needed, the Wastegate Solenoid will direct more of the boost pressure to the clean air tube upstream of the Turbocharger and less against the Wastegate spring.
- When Monitored:
With the engine running and DTCs P0033, P0034, P0035, P0237, P0238, P0299, P006C, P006D, P012B, P1185, P2261, P2262 are not present.
- Set Condition:
The PCM detects that the difference between the Boost Pressure Sensor desired value minus the actual reading is above a calibrated value for the driving conditions.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. CHECK FOR ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, clear DTCs in the Powertrain Control Module.
3. Test drive the vehicle.
4. With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 2
No
- Perform the INTERMITTENT DTC Diagnostic Procedure. Intermittent Condition Test.
2. CHECK THE AIR FILTER
1. Turn the ignition off.
2. Remove and inspect the Air Filter and housing inlet for snow, soiling or excessive dirt and debris which may cause air flow restriction.
Were any of these problems found?
Yes
- Replace the Air Filter or remove the obstruction.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
3. CHECK FOR INTAKE SYSTEM LEAKS OR RESTRICTIONS
NOTE: Damaged, restricted or poorly connected Intake System and Turbocharger System related tubes can cause this DTC to set.
1. Inspect all air intake, crankcase vent and Turbocharger related hoses/tubes and clamps for leaks or damage.
2. Inspect all boost pressure system hoses for leaks or restrictions.
3. Inspect the Intercooler Assembly for signs of a leak.
Were any problems found?
Yes
- Repair or replace as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. CHECK FOR EXHAUST SYSTEM RESTRICTIONS
1.
2.
3. Inspect the complete exhaust system for damaged, bent or clogged pipes that can cause exhaust system restrictions and excessive back pressure.
Were any problems found?
Yes
- Repair or replace as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 5
5. WASTEGATE AND SOLENOID INSPECTION
1. Inspect the Wastegate Solenoid, linkage and the Wastegate for proper operation. Refer to the appropriate service information.
2. Inspect and test each of the Wastegate Solenoid vacuum/pressure hoses between the engine, the Wastegate Solenoid and the Wastegate Valve.
3. Inspect and test each of the Wastegate Solenoid electrical circuits between the solenoid connector and PCM C1 harness connector.
NOTE: Test each electrical circuit for high resistance, a short to ground and a short to voltage.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test.
No
- Repair or replace the Turbocharger.
- Perform the PCM VERIFICATION TEST. Powertrain Verification Test.