OBD2 monitors are diagnostic tests run by your car’s computer to ensure the emission system is working correctly. This comprehensive Obd2 Monitors List explains each monitor’s function, helping you understand how your vehicle maintains optimal performance and emissions. Understanding this list can be invaluable when using an OBD2 scanner.
OBD2 Monitor Types and Functions
Your vehicle’s onboard diagnostic system continuously runs various tests categorized into two main types: continuous and non-continuous monitors. Continuous monitors run constantly while the engine is running, while non-continuous monitors require specific driving conditions to initiate. Here’s a breakdown of common OBD2 monitors:
Continuous Monitors
- Oxygen Sensor Monitor: Measures the oxygen content in the exhaust to adjust the air/fuel mixture for optimal combustion and reduced emissions. A faulty sensor can lead to poor fuel economy and increased emissions.
- Oxygen Sensor Heater Monitor: Ensures the oxygen sensor reaches operating temperature quickly for accurate readings. A malfunctioning heater can delay the closed-loop operation, impacting emissions and performance. This monitor is specific to spark ignition vehicles.
Non-Continuous Monitors
- Catalyst Monitor: Evaluates the catalytic converter’s efficiency in converting harmful pollutants into less harmful substances. A failing catalytic converter will trigger this monitor. This applies to spark ignition vehicles.
- Evaporative System Monitor: Checks for leaks in the fuel system that can release harmful vapors into the atmosphere. This monitor typically runs when the vehicle is parked.
- EGR System Monitor: Monitors the Exhaust Gas Recirculation (EGR) system, which reduces nitrogen oxide emissions. This monitor ensures proper EGR valve function and flow. Applies to spark ignition vehicles.
- Secondary Air Injection (AIR) System Monitor: Checks the functionality of the secondary air injection system, which injects air into the exhaust during cold starts to aid catalytic converter warm-up and reduce emissions. Applies to spark ignition vehicles.
Diesel Engine Specific OBD2 Monitors
Diesel engines have unique monitors tailored to their emission control systems:
- NMHC Catalyst Monitor: This monitor, specific to compression ignition vehicles, checks the Non-Methane Hydrocarbon (NMHC) catalyst’s efficiency in reducing harmful emissions.
- NOx Aftertreatment Monitor: Monitors the effectiveness of the system designed to reduce nitrogen oxide emissions in diesel vehicles.
- Boost Pressure System Monitor: Ensures the turbocharger or supercharger system, crucial for diesel engine performance, is operating within the correct parameters.
- Exhaust Gas Sensor Monitor: Checks the performance of various exhaust gas sensors specific to diesel engines, including the NOx sensor.
- PM Filter Monitor: Monitors the Diesel Particulate Filter (DPF), responsible for trapping soot particles from the exhaust. This monitor checks for proper regeneration and filter health.
Two-Trip Monitors and Pending Codes
Many OBD2 monitors are “two-trip” monitors. This means the fault must be detected on two consecutive drive cycles before a Diagnostic Trouble Code (DTC) is stored and the Check Engine Light (MIL) illuminates. A fault detected on a single trip is stored as a pending code.
Conclusion: Leveraging the OBD2 Monitors List
This obd2 monitors list provides a foundation for understanding how your vehicle’s diagnostic system works. By utilizing an OBD2 scanner and interpreting the monitor status, you can gain valuable insights into your vehicle’s health, address potential issues proactively, and ensure optimal performance and emissions compliance. Regularly checking the status of these monitors can help you avoid costly repairs and keep your car running smoothly. Remember to consult your vehicle’s specific repair manual for detailed information about your car’s OBD2 system.
