What this code means
P0299 means the difference between target and actual boost pressure is outside the specified range.
P0299 concerns the difference between target boost pressure and actual boost pressure. The controller has an expected target, and the stored condition means the difference from the actual result is outside the specified range. The diagnosis works through the components and paths listed for that underboost condition.
The guide includes air-cleaner condition, bypass and purge components, leak inspections, wastegate operation and bypass-solenoid operation. These are separate inspection areas within the same diagnostic path. Their findings need to remain separate so that the remaining-component conclusion can be applied under its stated condition.
What the vehicle may do
- The PCM can store P0299 for an out-of-range boost difference.
Possible fault areas
- Possible fault areas include the air cleaner element and boost systems.
- The turbocharger and turbocharger wastegate control actuator may be involved.
- The turbocharger bypass control valve and turbocharger bypass control solenoid valve may be involved.
- The EVAP canister purge valve, EVAP purge system, and exhaust system may be involved.
- The PCM may also be involved.
The earlier component checks lead into a confirmation using the recorded operating conditions. The leak inspections then address their named system areas. Keep the regional configuration noted for the EVAP purge-system check with that inspection.
The later operation checks ask whether the actuator or solenoid performs the stated function. A visual-condition finding, a leak result and an operation result are different kinds of evidence. Follow their individual normal or abnormal criteria before moving to the final conclusion.
Diagnostic path
Understand the stored condition
P0299 means Turbocharger Underboost Problem. The PCM compares the target boost pressure with the actual boost pressure. If the difference is outside the specified range, the PCM stores this code.
Understanding the component view
This component overview shows USA/Canada models.
Air cleaner element
Start with the Air Cleaner Element Inspection.
Bypass control valve
Next, complete the Turbocharger Bypass Control Valve Inspection.
Canister purge valve
Then complete the EVAP Canister Purge Valve Inspection.
Bypass control solenoid valve
Next, complete the Turbocharger Bypass Control Solenoid Valve Inspection.
Recreating the recorded conditions
Start the engine. Hold the engine speed at 3,000 rpm without load, in neutral, until the radiator fan comes on. Then test-drive the vehicle under the same conditions recorded in this DTC's on-board snapshot. Use the HDS path PGM-FI, then Data List. The signals are Vehicle Speed, ECT Sensor 1, MAP Sensor (Hi Res), TC Boost Pressure, and Engine Speed.
This stage ties the fault check to the on-board snapshot conditions. Use the listed parameters as the reference for the operating point being reproduced. The resulting status observation is most useful when it remains associated with those conditions, rather than being treated as a general observation made during any drive.
EVAP purge system leaks
For the EVAP purge-system check, retain the USA/Canada configuration. Look for poor connections at hose and pipe joints. Possible major leak areas also include incorrectly installed, deformed, or damaged components and devices, including sensors. That includes hoses, tubes, and pipes. Also check locations where gaskets are used. The normal result is no leaks. If this check is abnormal, there is a problem with the EVAP purge system.
This inspection belongs to the particular system area named in the heading. Keep the stated connection, condition or leak criterion with that area. The sequence separates these possible paths so that a finding in one area is not mistaken for the result of another inspection.
Boost system 1 leaks
Check the boost system components between the turbocharger and the throttle body for leakage. Look for poor connections at hose and pipe joints. Possible major leak areas also include incorrectly installed, deformed, or damaged components and devices, including sensors. That includes hoses, tubes, and pipes. Also check locations where gaskets are used. The normal result is no leaks. If this check is abnormal, there is a problem with boost system 1.
Boost system 2 condition
Now check the boost system 2 components for poor connections, blockage, restriction, leakage, or damage. The connections should be in good condition. There should be no blockage, restriction, leakage, or damage. If this check is abnormal, there is a problem with boost system 2.
Exhaust system leaks
Check for leakage along the exhaust system, from the engine to the outlet of the muffler. Look for poor connections at hose and pipe joints. Possible major leak areas also include incorrectly installed, deformed, or damaged components and devices, including sensors. That includes hoses, tubes, and pipes. Also check locations where gaskets are used. The normal result is no leaks. If this check is abnormal, there is a problem with the exhaust system.
Wastegate actuator operation
On the HDS, select PGM-FI, then Function Test, then Electric Waste Gate. Run Electric Waste Gate and watch the wastegate actuator. The actuator should operate. If its operation is abnormal, there is a problem with the turbocharger.
Bypass solenoid operation
Boost system 2 must be normal for this test. You can run this test before completing any other inspections because it includes all the inspection items. If it fails, continue with each inspection item individually to find which item failed. On the HDS, select PGM-FI, then Function Test, then TC BYPASS CONTROL SOL.V. TEST. Run TC BYPASS CONTROL SOL.V. TEST and listen for a clicking noise from the bypass solenoid valve. Clicking is the normal result.
If this check is abnormal, there is a problem with the turbocharger bypass control solenoid valve.
When the other checks are normal
If the other inspection items are normal, this diagnostic path identifies the PCM as the remaining cause.
Final check
Possible fault areas include leaks, boost-system restrictions or damage, turbocharger controls, and the PCM.
The completed diagnosis should show which component or system-area check produced an abnormal finding. If the procedure reaches its final remaining-component branch, retain the prerequisite that the other checks were normal. This connects the target-versus-actual boost issue to the specific inspections that support the conclusion.
