Emissions System Components
PCV
The Positive Crankcase Ventilation (PCV) system is a crucial part of the vehicle’s emissions control and air intake system. Its main function is to reduce emissions by preventing crankcase vapors from being released into the atmosphere. During combustion, fuel vapors build up in the crankcase, and the PCV system reroutes these vapors back into the intake manifold. Once there, they are mixed with the air/fuel mixture and consumed during the combustion cycle. This not only reduces harmful emissions but also improves fuel efficiency by burning vapors that would otherwise be lost. A malfunctioning PCV valve can lead to poor engine performance, increased oil consumption, and higher emissions.
The Evaporative Emission (EVAP) control system prevents fuel vapors from escaping into the atmosphere by capturing them in a charcoal canister. These vapors are stored in the canister when the vehicle is off or idling. Once the vehicle is running and conditions are optimal, the engine vacuum draws these vapors from the canister into the intake manifold, where they are burned during the combustion process. This system helps reduce hydrocarbon emissions, which are a major contributor to smog. Common issues with the EVAP system can trigger the check engine light and result in diagnostic trouble codes such as P0441 or P0442, indicating potential leaks or issues with purge flow. Click here to READ MORE!
EGR
The Exhaust Gas Recirculation (EGR) system is an essential component for reducing nitrogen oxides (NOx) emissions, which are harmful pollutants contributing to smog and air pollution. The EGR system lowers the combustion temperature in the engine by recirculating a portion of the exhaust gases back into the engine’s combustion chambers. By reducing the combustion temperature, the production of NOx is minimized. The EGR valve regulates the flow of exhaust gases into the intake manifold. When it malfunctions, it can cause engine roughness, increased emissions, and a noticeable loss in fuel efficiency.
Emission System Check Engine Light Codes
| P0441 | Evaporative Emission Control System Incorrect Purge Flow |
| P0442 | Evaporative Emission Control System Leak Detected (small leak) |
| P0446 | Evaporative Emission Control System Vent Control Circuit Malfunction |
| P0455 | Evaporative Emission Control System Leak Detected (gross leak) |
Common Emission System Problems and Solutions
- PCV System Failure: If the PCV valve becomes clogged or stuck, it can cause engine oil contamination, higher emissions, or rough idling. Replacing the PCV valve is a simple fix that improves engine health and emission control.
- EVAP System Leaks: A loose gas cap or a damaged hose in the EVAP system can trigger a check engine light and cause a P0442 code. The solution may be as simple as tightening the gas cap, but a professional diagnosis is recommended to detect leaks in the system.
- EGR Valve Issues: Carbon buildup in the EGR valve can cause it to stick open or closed, leading to increased NOx emissions and poor engine performance. Cleaning or replacing the EGR valve can restore proper function.
- Catalytic Converter Failure: If the catalytic converter becomes clogged or damaged, it can severely reduce engine performance and cause the check engine light to illuminate. Replacing the catalytic converter is often necessary when it fails.
Contact Hollenshade’s for Emissions System Repair
If you’re experiencing issues with your vehicle’s emissions system or have a check engine light related to emissions components, Hollenshade’s can help. Our certified technicians specialize in diagnosing and repairing PCV, EVAP, EGR systems, and more. We provide expert services to ensure your vehicle meets emissions standards and runs efficiently. Make an appointment at our Townson mechanic shop today.
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