The P04DB code indicates an issue with the crankcase ventilation system, which may be affected by the installation of the CAI. Here are a few steps you can take to troubleshoot and potentially resolve the issue:
1. **Check Connections**: Ensure that all connections related to the crankcase ventilation system are secure and properly connected. Look for any loose or disconnected hoses that could be causing a vacuum leak.
2. **Inspect Air Intake Components**: Examine the CAI installation to make sure everything is fitted correctly. Ensure that the intake air temperature sensor and any associated connectors are firmly in place.
3. **Verify Vacuum Lines**: If your vehicle has any vacuum lines connected to the intake manifold or elsewhere, make sure these are intact and not damaged or disconnected.
4. **Reinstall the OEM Air Intake**: If the CEL persists after checking everything, it may be worthwhile to reinstall the original air intake system temporarily. This can help determine if the issue is indeed related to the CAI installation.
5. **Clear Codes Again**: After checking and making any adjustments, clear the codes and see if they return after a short drive. Personally I like to use my Youcanic Full System Scanner, as this tool is excellent for diagnosing a wide array of systems in my vehicle and can help pinpoint the trouble effectively.
6. **Consult a Professional**: If you're still experiencing issues and the code keeps coming back, it may be beneficial to consult a mechanic who has experience with performance modifications or emissions systems.
