DTC P0234 or P0299 (LLU)
| DTC P0234 or P0299 (LLU) |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptors |
DTC P0234 00
Engine Overboost
DTC P0299 00
Engine Underboost
| Diagnostic Fault Information |
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
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5 V Reference
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P0237 00
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P0036 00, P0606 00
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Signal Circuit
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P0237 00
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P0237 00, P0238 00
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P0238 00
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P0234 00, P0299 00
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Low Reference
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P0098 00, P0234 00, P0238 00
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| Typical Scan Tool Data |
Turbocharger Inlet Pressure Sensor Circuit
| Circuit | Short to Ground | Open | Short to Voltage |
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Operating Conditions:
Engine running
Parameter Normal Range: BARO to 240 kPa (34.80 PSI) |
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5 V Reference
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20-80 kPa (2.9-11.60 PSI)
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30-80 kPa (4.35-11.60 PSI)
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20-80 kPa (2.9-11.60 PSI)
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Signal Circuit
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0 kPa
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276 kPa (40 PSI)
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276 kPa (40 PSI)
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Low Reference
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-
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276 kPa (40 PSI)
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| Circuit/System Description |
The boost pressure sensor is integrated with the intake air temperature (IAT) sensor. The boost pressure sensor measures the range of pressures between the turbocharger and the throttle body. The sensor used on this engine is a three atmosphere sensor. Pressure in this portion of the induction system is affected by engine speed, throttle opening, turbocharger boost pressure, intake air temperature (IAT), barometric pressure (BARO), and the efficiency of the charge air cooler. The boost pressure sensor and integrated intake air temperature (IAT) sensor have the following circuits:
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5 Volt Reference
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Low Reference
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Intake air pressure signal
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IAT sensor signal
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The boost pressure sensor provides a signal voltage to the engine control module (ECM), relative to the pressure changes, on the intake air pressure signal circuit. During normal operation, the highest pressure that can occur in this part of the intake manifold with the ignition ON and the engine OFF is equal to the barometric pressure (BARO). When the vehicle is run with wide open throttle (WOT) , the turbocharger can increase the pressure to close to 240 kPa (34.80 psi). The least pressure that occurs is when the vehicle is idling or decelerating, and it is equal to the BARO.
| Conditions for Running the DTC |
P0234 00
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DTCs P0237 00, or P0238 00 are not set.
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The driver requested boost pressure level exceeds the level of the base boost pressure.
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This DTC runs continuously within the enabling conditions.
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P0299 00
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DTCs P0237 00, P0238 00, P0244 00, P0245 00, P0246 00, P2228 00, or P2229 00 are not set.
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The BARO is greater than 65 kPa (9.42 PSI).
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The engine speed is between 2 600-3 120 RPM.
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The ECM is not in limp home mode.
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The ECM is not in limp home mode with safety fuel cut-off activated.
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The driver requested boost pressure level exceeds the level of the base boost pressure.
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This DTC runs continuously within the enabling conditions.
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| Conditions for Setting the DTC |
P0234 00
The ECM detects that the actual boost pressure is greater than the desired boost pressure for greater than 2 s.P0299 00
The ECM detects that the actual boost pressure is less than the desired boost pressure continuously.| Action Taken When the DTC Sets |
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DTCs P0234 00 and P0299 00 are Type C DTCs.
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The ECM will disable boost control and limit the system to mechanical boost only, resulting in a substantial decrease in engine power.
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The service vehicle soon indicator will illuminate.
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| Conditions for Clearing the DTC |
DTCs P0234 00 and P0299 00 are Type C DTCs.
| Diagnostic Aids |
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The boost pressure sensor signal circuit is pulled high in the ECM. With the sensor disconnected, at ignition ON, a normal voltage measurement of the signal circuit with a DMM is 5.60 V.
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The charge air cooler is connected to the turbocharger and to the throttle body by flexible duct work that requires the use of special high torque fastening clamps. These clamps cannot be substituted. In order to prevent any type of air leak when servicing the duct work, the tightening specifications and proper positioning of the clamps is critical, and must be strictly adhered to.
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Use a solution of dish soap and water in a spray bottle to pinpoint any air leaks.
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| Reference Information |
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
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Turbocharger System Description (LLU)
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Boost Control System Description (LLU)
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Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Verification |
| 1. |
Verify that restrictions do not exist in the exhaust system. Refer to
Restricted Exhaust
.
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| 2. |
If DTC P0299 00 is set, verify the proper operation of the charge air bypass valve.
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| 3. |
Use the scan tool output controls to command the Turbocharger Bypass Solenoid Valve to 100% and then back to 0%. An audible series of clicks should be heard and felt between 20-90%.
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| 4. |
Use the scan tool output controls to command the Turbocharger Wastegate Solenoid Valve to 100% and then back to 0%. An audible series of clicks should be heard and felt between 20-90%.
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| 5. |
Determine the current vehicle testing altitude. Ignition ON, observe the scan tool manifold absolute pressure (MAP) Sensor parameter, the Boost Pressure Sensor parameter, and the BARO Sensor parameter. Compare the parameters to each other and to the
Altitude Versus Barometric Pressure
table.
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| 6. |
Use the scan tool and compare the MAP Sensor parameter to the Boost Pressure Sensor parameter during a WOT acceleration. The readings should be within 20 kPa (2.9 PSI) of each other.
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| 7. |
Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
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| Circuit/System Testing |
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Verify the integrity of the entire air induction system including all turbocharger components by inspecting for the following conditions:
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Any damaged components, including the turbocharger, the charge air cooler, and the Q42 Turbocharger Wastegate Solenoid Valve
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Any hairline fractures of the B111 Turbocharger Boost Sensor housing
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Loose or improper installation of any components
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An air flow restriction
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Any vacuum leak
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Any pinholes or breaks in the vacuum hoses attached to the Q42 Turbocharger Wastegate Solenoid Valve
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Any restrictions in the vacuum hoses attached to the Q42 Turbocharger Wastegate Solenoid Valve
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Improper routing or connecting of the vacuum hoses on the charge air cooler, the Q40 Turbocharger Bypass Solenoid Valve, and the Q42 Turbocharger Wastegate Solenoid Valve
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Any type of air leak between the turbocharger and the throttle body, including the charge air cooler assembly
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Verify that an exhaust leak does not exist, including the mating surface area between the turbocharger and the exhaust manifold.
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| 2. |
Ignition OFF, disconnect the harness connector at the B111 Turbocharger Boost Sensor.
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| 3. |
Ignition OFF for 90 s, test for less than 5 Ω between the low reference circuit terminal 1 and ground.
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| 4. |
If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
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| 5. |
Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.
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| 6. |
If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
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| 7. |
If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
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| 8. |
Verify the scan tool Turbocharger Inlet Pressure Sensor parameter is greater than 275 kPa (39.9 PSI).
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| 9. |
If less than the specified range, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
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| 10. |
Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 1. Verify the scan tool Turbocharger Inlet Pressure Sensor is less than 1 kPa (0.14 PSI).
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| 11. |
If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
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| 12. |
If all circuits/connections test normal, replace the B111 Turbocharger Boost Sensor.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Turbocharger Pressure Sensor Replacement (LLU/A16LET)
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Turbocharger Wastegate Regulator Solenoid Valve Replacement (LLU/A16LET)
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Control Module References
for ECM replacement, setup, and programming
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