Technical Description of OBD-II Trouble Code
Condition of Turbocharger/Supercharger B Underboost
What is the meaning of this?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to OBD-II equipped vehicles with a turbocharger or supercharger. It can affect various brands of vehicles including Ford, GMC, Chevy, VW, Audi, Dodge, Hyundai, BMW, Mercedes-Benz, Ram, etc. Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
The P0299 DTC code indicates that the PCM/ECM (powertrain/engine control module) has detected that the “B” turbocharger or supercharger is not providing the normal amount of boost.
Refer to a vehicle-specific repair manual to determine which turbocharger or supercharger is labeled as “B” in your particular application. There can be several reasons for this condition, which are explained below. In a normally operating turbocharged or supercharged engine, the air going into the engine is pressurized, contributing to its high power output relative to its size. If this code is set, you will likely experience reduced power output.
For Ford vehicles, the following may apply: “The PCM checks for a minimum throttle intake pressure (TIP) PID reading during engine operation, which indicates an underboost condition. This DTC sets when the PCM detects that the actual throttle intake pressure is less than the desired throttle intake pressure by 4 psi or more for 5 seconds.”
Symptoms
The symptoms of a P02CB DTC may include:
There are unlikely to be any other symptoms.
Potential Causes
The potential causes of a P02CB turbo underboost code include:
Possible P02CB Solutions
Firstly, it is recommended to address any other DTC codes that may be present before diagnosing this code.
Begin with a visual inspection. Check the intake air system for cracks, loose or disconnected hoses, restrictions, blockages, etc. Repair or replace as necessary.
If the air induction system passes the inspection, focus the diagnosis on the charge pressure control, diverter valve (blowoff valve), sensors, regulators, etc. At this point, it is advisable to refer to a vehicle-specific detailed repair manual for specific troubleshooting steps. Certain makes and engines may have known issues, so it is also helpful to search car repair forums using relevant keywords. For example, in VWs, a common fix for a P0299 is to replace or repair the diverter valve or wastegate solenoid. In GM Duramax diesel engines, this code may indicate a failure of the turbo housing resonator. For Ford vehicles, it is recommended to check the wastegate regulating valve solenoid for proper operation.
