An OBD2 Readiness monitor is a self-diagnostic emission monitoring system in a vehicle having a standard OBD2 system (SAE J1979).
The Readiness monitor checks whether the emissions control systems (EGR, EVAP, etc) are working correctly.
Most modern cars have the Readiness monitor look over up to 11 emission tests to make sure the car’s harmful emission levels are kept low. (as seen in the image below)
Most Countries (i.e The United States, Australia, etc) require an annual or biannual vehicle emission inspection for the car to be legally driven on the roads, hence, it is very necessary to make sure the Readiness monitors are performing well.
In simple words, a Readiness monitor is a collection of monitoring systems that work together to check the status of a vehicle’s emissions control systems.
You can perform a readiness monitor check with & without an OBD-II scanning tool. (refer to V. Readiness monitor operation for a detailed tutorial)
Purpose of Readiness Monitors
Despite having environmental benefits, having a functioning readiness monitor system can also help to improve the vehicle’s overall performance and fuel efficiency.
The Readiness monitor uses Oxygen sensors, EGR system reading, and temperature sensors to make sure:
- The engine is completely utilizing the oxygen it is receiving.
- There are no misfires.
- Using Temperature sensors present inside EVAP & EGR systems to make sure the car is not overheating.
When the emissions control systems are operating efficiently, the vehicle’s engine can run more smoothly, resulting in better fuel economy and overall performance.
In summary, the purpose of having a readiness monitor system in your car is to ensure that the vehicle’s emissions control systems are functioning properly, to reduce harmful emissions, and to improve overall performance and fuel efficiency.
Readiness monitors are important because they ensure that the vehicle’s emissions control systems are functioning correctly, which helps to reduce air pollution and the protection of public health.
In addition, passing a readiness monitor test is often a requirement for passing a vehicle emissions inspection as mentioned earlier.
Types of Readiness Monitors
Readiness monitors can be categorized into 2 basic categories based on how they perform their respective tasks:
Continuous & Non-Continous.
By definition, Continuous monitors are a type of readiness monitor that continuously check the status of a vehicle’s emissions control systems while the vehicle is in operation. These monitors are always active and constantly monitor the vehicle’s sensors and systems while the car is idle/in motion.
Miss-fire, fuel system & comprehensive component monitor falls under the category of continuous monitors.
Conversely, the non-continuous monitors require certain conditions to be met before a test or series of tests can be completed.
Evaporative (EVAP) System, Secondary Air System, Oxygen (O2) Sensors, Oxygen Sensor Heater, EGR (Exhaust Gas Recirculation), and/or VVT System falls under the category of non-continuous monitors.
The conditions necessary for the car to run these self-diagnostic tests vary. (detailed explanation present under V. Readiness monitor operation)
Readiness Monitor System Components
As mentioned earlier, A readiness monitor is a collection of monitoring systems that work together to check the status of a vehicle’s emissions control systems.
These monitoring systems can include continuous monitors and non-continuous monitors. Each of these monitoring systems serves a specific purpose in evaluating the health of the emissions control system, and together they provide a comprehensive picture of the system’s overall functionality.
- Engine misfires – monitors engine’s firing sequence and detects misfires.
- Fuel system monitor – monitors fuel pump, fuel injectors, etc to ensure proper fuel supply & utilization.
- Comprehensive component – monitors for malfunctions in any powertrain electronic component or circuit.
- Catalyst monitor – checks the performance of a vehicle’s catalytic converter.
- Evaporative emission monitoring system or EVAP – Prevents fuel vapors from escaping into the atmosphere, capturing and storing them in a charcoal canister.
- Oxygen (O2) sensors – Oxygen sensors measure the oxygen levels in a vehicle’s exhaust system and provide feedback to the engine control module to help maintain the optimal air-to-fuel ratio.
- Exhaust gas recirculation or EGR – Reduces engine emissions by recirculating some of the exhaust gases back into the engine’s combustion chamber.
- Secondary air injection or SAI – Reduces emissions by injecting fresh air into the exhaust system to help burn unburned fuel and reduce pollutants.
Readiness Monitor System Operation
The readiness monitoring system checks the status of various components in a vehicle’s emission control system, including the fuel system, catalytic converter, oxygen sensors, etc.
The readiness monitoring system then reports this data to the engine control module (ECM) through the onboard diagnostics (OBD) system.
If the readiness monitoring system detects an issue with any of the monitored components, it will set a diagnostic trouble code (DTC) and trigger a warning light on the dashboard to alert the driver.
After a memory reset is performed in a car’s OBD-2 system, the monitors will then require the car to go under a predefined “drive-cycle” routine to reperform a test diagnosis.
This “drive-cycle” routine varies on the car manufacturer but is subjective to small sessions of city/highway drive.
Steps to perform a Readiness check:
With an OBD2 scanner:
- Connect the OBD2 scanner to the vehicle’s OBD2 port, which is typically located under the dashboard on the driver’s side.
- Turn on the ignition, but do not start the engine.
- Follow the scanner’s prompts to check the readiness monitor status. The scanner will display the status of each monitor as “ready” or “not ready”.
- Perform a ‘drive-cycle’ if the scanner says ‘not ready’.
- Tap on the readiness monitor & the scanner will tell you the status of each sub-monitoring system (i.e EGR, EVAP, etc.)
Without an OBD2 scanner:
- Turn the ignition to the “on” position, but do not start the engine.
- If the “Check Engine” light blinks eight (8) times, then the monitors are ‘Not ready’ – You need to perform a ‘drive-cycle’ first.
- If the check engine light stays on solid, then the monitors are ‘Ready’.
- Then proceed to start the engine, If the check engine light or any other warning lights remain illuminated, there may be an issue with the readiness monitoring system.
- If no check engine light is illuminated upon starting the car then the readiness monitoring system is working fine.
Readiness Monitor Diagnostic Trouble Codes (DTCs)
DTC codes associated with a readiness monitoring system typically indicate that one or more of the emission control system monitors has not completed their diagnostic tests or that there is an issue with the system.
Some of the common DTC codes associated with readiness monitoring systems include:
It is best advised to consult a technician or an authorized person to perform a check on your car, the DTC codes mention above or anywhere else on the internet may differ up on the car manufacturer.
Importance of Maintaining Readiness Monitors
Maintaining readiness monitors is important for ensuring that a vehicle’s emissions control system is functioning properly and that the vehicle can pass an emissions test. When the readiness monitors are not ready, it indicates that the vehicle’s onboard diagnostics system has not completed its diagnostic tests, which could mean that there is an issue with the emissions control system.
To maintain the readiness monitors, it’s important to keep the vehicle in good condition and follow the manufacturer’s recommended maintenance schedule. This includes regular oil changes, replacing worn-out parts, and ensuring that the vehicle’s fuel and air systems are clean and functioning properly.
By maintaining the readiness monitors and ensuring that the emissions control system is functioning properly, not only will the vehicle be able to pass an emissions test, but it will also run more efficiently and produce fewer harmful emissions, which is better for the environment.
A Readiness monitor is a self-diagnostic emission monitoring system in a vehicle that checks whether the emissions control systems are working correctly. A functioning readiness monitor system can help to improve the vehicle’s overall performance and fuel efficiency.
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As a mechanical engineer, it’s easy for David to explain the functionality of the tool. David test most of the tools before writing a review. its help him to learn something new and suggest the best product for you.