What this code means
P0299 generally means the ECM/PCM may be seeing less boost response than it expects from the turbocharger system.
What the vehicle may do
- The vehicle may feel low on power.
- Acceleration may be weaker than normal.
- The warning light may come on with few other obvious symptoms.
Possible fault areas
- Possible air leakage or restriction in the boost path.
- Possible EVAP purge leakage influence.
- Possible exhaust leakage.
- Possible turbocharger wastegate control concern.
- Possible turbocharger bypass control solenoid concern.
- Possible PCM concern only after the other areas check normal.
Diagnostic path
Opening context
On this 2017 through 2025 Honda CR-V with the 1.5 turbo engine, P0299 is a turbocharger underboost problem. In plain terms, the ECM/PCM may be seeing actual boost pressure fall outside what it is targeting. The driver may notice weak acceleration, reduced power, or the light may simply come on. Broadly, this can involve possible leakage, restriction, or damage in the EVAP purge path, the boost air path, the exhaust path, wastegate operation, bypass solenoid operation, or, only after the rest checks normal, the PCM side of the diagnosis. Start with the basic system checks and follow a structured diagnostic approach before getting into the individual inspections.
Reproduce the operating conditions
Begin by starting the engine. Then hold the engine speed at 3,000 rpm without load, in neutral, until the radiator fan comes on. After that, test-drive the vehicle under the same captured conditions for this DTC, paying attention to vehicle speed, ECT Sensor 1, MAP Sensor Hi Res, turbocharger boost pressure, and engine speed. The point here is to duplicate the conditions where the PCM saw target boost and actual boost disagree.
Check EVAP purge leakage first
Next, check the EVAP purge system components for leakage. You want no leaks here. Look for the usual leak contributors: poor hose or pipe connections, parts that are not seated correctly, deformed or damaged hoses, tubes, pipes, sensors, related devices, and gasketed joints. If this inspection is abnormal, stay with the EVAP purge system as the problem area instead of moving on like it passed.
Inspect the boost path between the turbo and throttle body
If the EVAP purge side checks out, move to the boost system between the turbocharger and the throttle body. Check for leakage, and the expected result is no leaks. If that inspection is abnormal, treat the boost path in that section as the fault area.
Inspect the rest of the boost system condition
Then check the boost system components for poor connections, blockage, restriction, leakage, or damage. The system should have good connections and no blockage, restriction, leakage, or damage. If this part of the inspection is abnormal, stay in that boost system fault area and do not skip past it.
Check exhaust leakage
After the boost-side checks, inspect the exhaust system from the engine to the outlet of the muffler for leakage. Again, the expected result is no leaks. Poor joints, damaged or distorted parts, and gasketed areas are the kind of places that can create a leak concern. If the exhaust inspection is abnormal, the exhaust system becomes the problem area for this diagnostic path.
Command the wastegate actuator
Next, use the HDS Electric Waste Gate function and visually check the turbocharger wastegate control actuator. The actuator should operate. If it does not operate during that functional check, the diagnostic path points to a turbocharger problem area. Do not call the PCM until this mechanical and actuator-side check has been handled correctly.
Run the bypass control solenoid test
Now run the HDS TC Bypass Control Solenoid Valve test. The expected result is a clicking noise from the valve. This check assumes boost system 2 is normal. The bypass solenoid function test can be run earlier in the process, but if it fails, keep going through the individual inspections so you know which item actually failed. If this inspection is abnormal, the problem area is the turbocharger bypass control solenoid valve.
PCM only after the rest checks normal
If the other inspection items all indicate normal condition, then inspect the PCM as the remaining cause. That is the end of the diagnostic path, not the starting point. Work through the leaks, restrictions, actuator operation, and solenoid operation first, then evaluate the PCM only if those checks did not identify the fault area.
Verification and takeaway
Keep verification separate from the component inspections. After the fault area has been addressed, go back to the same warm-up and captured test-drive conditions and verify the repair and confirm the code stays gone. The takeaway on P0299 is simple: prove the operating condition, check for air and exhaust path problems in order, command the turbo controls, and leave PCM judgment for last. For more diagnostic training, visit stepdiagnostics.com.
Final check
P0299 is often a command-versus-response diagnosis: reproduce the condition, check the air and exhaust paths, then verify the turbo control functions before considering the PCM.
For more guided automotive diagnostics, visit STEP Diagnostics.
