Ever heard of OBD2 readiness monitors? These monitors are present in every vehicle. They are simple but efficient monitors which conduct powerful self-tests in every car. Their self-tests help monitors any car emission control system problems and ensures they work in good conditions, or else, you might notice a “monitor EVAP not ready” error.
An evaporative emission control system (EVAP) is a very important system that prevents fuel vapor from escaping to the atmosphere when the engine is idle or running. “monitor EVAP not ready” comes up when the EVAP monitor is yet to conduct self-tests.
The EVAP system monitor is one of the OBD2 readiness monitors. It might be activated when a canister is purged (unless you require a canister purge valve replacement). This occurs during normal engine conditions or when the vehicle is operating normally.
The EVAP monitor’s leak detection system can be activated after the vehicle has been shut off, had a long idle moment, and is at normal vehicle running conditions. As expected with typical OBD2 monitors, all electrical components are tested, as well as any faults that might appear during a continuous monitoring process.
“Monitor EVAP not ready” gives you the idea that your vehicle might not pass emission tests since the evaporative emission control system is yet to be activated and the emission control systems do not detect fuel vapor leaks.
In this article, you will learn all the tricks in getting your evaporative emission control system (EVAP) monitors ready for the various self-tests.
OBD2 Readiness Monitors are of two types: non-continuous monitors and continuous monitors.
Continuous monitors, as their name suggests, run self-tests and look for problems while your car is running. The results from these tests are continuously evaluated while the engine is running.
There are presently 3 of these monitor types available in most cars. That includes fuel system readiness monitors, cylinder misfire monitors, and total component check sensors.
Non-continuous readiness monitors are built differently. They don’t “continuously” run self-tests as the engine is running. They instead have predefined conditions that must be met before they are activated.
These conditions vary from one monitor to the other. For some, the vehicle has to complete a preset drive cycle. Some require it to be 2 cycles or more. Follow these rules carefully to finish a test and avoid getting an incomplete readiness test.
The Evaporative Emission Control System (EVAP) is among numerous non-continuous OBD2 readiness monitors, requiring preset conditions for it to be activated. Other monitors include a catalyst monitor, secondary air system, oxygen (O2) sensors, exhaust gas recirculation system (be diligent of the bad EGR valve symptoms), boost pressure monitor, exhaust gas sensor, PM filter, and NMHC catalyst monitor.
EVAP Monitor Not Ready
Your vehicle will be rejected at any emissions test station once the information “monitor EVAP not ready” is displayed by the scan tool. This error means your car does not check fuel vapor and other emissions. So, do take a moment to understand what states do not require vehicle inspections.
Since preset conditions must be met before this monitor becomes ready, the EVAP monitor might be unready after the battery is disconnected or after fault codes become cleared from the Engine Control Module (ECM) memory. If certain conditions are not met later, the EVAP monitor will not be ready.
The EVAP monitor, when ready, checks for fuel vapor leaks using two methods:
- Conducting a pressure test on the fuel system
- Conducting a vacuum test on the system.
Using either involves applying pressure and vacuum to the fuel tank, EVAP charcoal canister (be wary of the bad charcoal canister symptoms), or vapor lines. Suppose no airflow is detected when the evaporative emission control system (EVAP) canister valve is opened or a leak equals or exceeds the air quantity required to pass a 0.040-0.020-inch hole.
In that case, a DTC fault code is prepared and stored by the Engine Control Module (ECM). A DTC fault code detected in 2 drive cycles will trigger the “check engine light” to come on.
How To Activate Your EVAP Monitor
Getting the EVAP readiness monitor activated depends on the vehicle’s model, year, and make. However, for starters, there needs to be about ¼ to ¾ fuel in your gas tank remaining. That is because an empty or full tank will affect the results of the EVAP self-tests.
To activate your EVAP monitor, follow the steps below.
Run Inspection And Maintenance Diagnostics
The first step is to run a system inspection/maintenance procedure. That enables you to satisfy all eligibility criteria to execute inspection and maintenance readiness diagnostics. After completing these tests, the inspection and maintenance system status indicators turn to “yes.” A negative result returns the letter NO.
Using a scan tool, you must observe all inspection and maintenance monitors and compare results with a data list. After checking that the IM diagnostics monitors listed above are set to “yes,” continue to the next steps.
The monitor EVAP not ready can be fixed when certain conditions are met in a preset order. We will analyze these conditions for better understanding. Remember we also mentioned how EVAP monitors could be activated by one or more drive cycles?
A drive cycle explains the cycle of a car from rest or idle moment to ignition and vehicle movement, then back to rest again. Here are some of the conditions that must be met for a procedure to be counted as positive while the EVAP monitor is on.
Monitor EVAP Not Ready: Cold Starts
- Barometric pressure is above 75 kPa
- Ignition voltage should be between 11 and 18 volts
- Atmospheric temperature is between 4 to 30 degrees centigrade
- ¼ or ¾ fuel tank level
- The alcohol content in fuel without RPO LMG equals 14% or less
- Alcohol content with RPO LMG equals 86% or less
- Engine coolant temperature is set at 4 to 30 degrees centigrade
- The air intake temperature should be at the same recommended atmospheric temperature.
When these conditions are met for a cold start during a drive cycle, the EVAP System Monitor counts it as a Plus. It also gets ready for the next activating stage.
At this point, all inspection and maintenance system indicators should report “yes” when checked with a scan tool.
Procedure: Phase 1
- Turn on the ignition and check if the positive voltage was supplied to the oxygen sensors. Put it off if it meets these criteria and allow resting for about 5 minutes before proceeding to the next step.
- Ensure your vehicle is in tandem with the conditions necessary for a cold start to be counted in one drive cycle.
- Check for the O2 system status report. If it is a NO, ensure the ignition is turned OFF for 10 hours. A YES report indicates you can move to the next step.
- Perform EVAP Service Bay test if available. If it is unavailable, buckle your belt for a marathon of 6 drive cycles with at least 17 hours between each drive cycle. The EVAP I/M system should report a YES after doing the latter.
- Set the vehicle at “park” for automatics or “neutral” for manual transmissions.
- Turn off all accessories, including Electrical, HVAC system, etc.
- Turn on the ignition and start the engine. Let it wait 2 minutes and wait for the temperature to reach 65 degrees centigrade.
- Throttle the engine for about 7 minutes and keep the revolutions per Minute (RPM) at 1,000 to 3,000 rpm. You would want to watch this step closely to avoid rendering your efforts void and repeating the whole process.
- Allow the engine to warm up for about 1 minute.
Procedure: Phase 2
- Gently hold the brake pedal, engage the gear to “drive” for automatic transmissions, and hold the clutch pedal for manual transmissions. Keep in this state for 2 minutes, carefully observing a steady RPM of 1200 to 2000, 15 to 30 g/s MAf signal range, and a TP sensor angle above 2%.
- Gently release the throttle pedal and place the vehicle to “Park” or “Neutral” for automatic or manual transmissions, respectively.
- The engine should be left idle for about 120 seconds. Take note not to touch the accelerator pedal during any idling time.
- Now drive the vehicle at about 24 km/hr or slower for 120 seconds.
- Increase speed to 45 – 112 km/h for the next 5.5 miles. Make sure you reach speeds of 80km/hr or above during this procedure.
- Stop accelerating and release the throttle for 2 seconds. That makes the vehicle activate a decel fuel cut-off mode.
- TP sensor angle should be increased by 3 to 20 percent by pressing the throttle pedal for about 1 minute.
- It is time to stop the vehicle. Leave the gear in “drive” or “neutral” and apply your parking brake. Leave the engine idle for 120 seconds.
- After 2 minutes, turn off the ignition and exit the car. Disturbing the ignition before you are told to do so will invalidate the whole process. Wait for 45 minutes before turning the ignition ON again.
By now, if you have followed all the procedures outlined above, all I/M system status monitors should indicate a “yes.” If otherwise, turn the ignition off for at least 17 hours and wait for all cold-start conditions to be met, then repeat the process. Keep repeating these steps until a “yes” report is indicated.
OBD Drive Cycle
If “monitor EVAP not ready” is indicated by the scan tool after repeating the above processes. Refer to the System DTC table associated with each monitor and follow instructions as seen in the manual, or take your car to an expert for professional servicing.
OBD drive cycles enable the powertrain control module (PCM) to check the readiness of all monitors and conduct self-tests. Drive cycles mimic a normal vehicle operation scenario.
Drive cycles vary according to year, model, and vehicle brand, but the basic drive cycle count is almost the same for all vehicle models. Since numerous monitors undergo tests during a drive cycle, different drive cycle patterns exist for different monitors.
Find your vehicle’s drive cycle pattern in the owner’s manual booklet. Almost all monitors are ready after a few miles when a brand-new car is used. That is because it will have completed various drive cycles unknown to the driver.
The “monitor EVAP not ready” condition can be corrected using a complete drive cycle or may require more cycles. You may use a generic drive cycle if the specific personalized drive cycle is not known. The cons of this are that it may not work for all vehicles and monitors.
Generic Drive Cycle
If you don’t know your vehicle’s drive cycle pattern, you may use this.
- A cold start: for a cold start to be counted, all previously mentioned requirements are to be met (atmospheric temperature is between 4 to 30 degrees centigrade, coolant temperature should be below 122 F, etc.).
- Turn on the ignition key. If the ignition key has been on before this, turn it off and wait a minimum of 10 hours. That is to enable the oxygen diagnostic monitor to function accurately.
- Start the engine and allow it to rev for 180 seconds. Put the Air Condition systems to ON if available.
- Turn the Air condition OFF and gently accelerate constantly to about 55mph. It should take a slow and steady pattern. Keep speed constant for about 3 minutes.
- Release the throttle pedal and allow the car to slow down without using the brake pedal. Allow deceleration down until 20 mph is achieved, and proceed to the next step.
- Press the accelerator pedal to 80 percent until you reach around 60 mph. Keep up this speed for the next 5 minutes.
- Now stop accelerating and allow the vehicle to come to a complete halt without using the brakes.
- Now return to the mechanic, repeating steps 4 to 7.
- Perform an OBD II scan to check if your vehicle is ready to pass the emissions test.
This procedure is to be carried out if, after a few miles, your vehicle still displays “monitor EVAP not ready.” This drive cycle enables the PCM to test readiness monitors and store DTC error codes continuously should any fault be found. Also, keep in mind that since it is a generic test, it might not check all monitors and may not work on all car models.
To avoid confusion, clear any old OBD II error codes from your scan tool before you drive. These error codes might include something like P0456 (especially for Dodge cars), P0446 (common on Toyota vehicles), P0457, P0446, P0449, P0440, P0496, or P0456, among other EVAP-related error codes.
To make sure the EVAP Readiness Monitor works well, try to keep your gas tank between 35 and 70 percent full. All internal combustion car engines do have a catalyst. Catalysts ensure that gas pollutants are oxidized using the oxygen from the exhaust pipe.
That helps reduce atmospheric pollution from carbon monoxide and other pollutants. Catalytic monitors help monitor the catalyst’s ability to carry out its job efficiently under normal working conditions.
Measuring the quantity of oxygen entering and leaving the diesel engine enables the Powertrain Control Module (PCM) to check the efficiency of the catalytic converter. That is sometimes a continuous process, and the engine light comes on when the catalyst monitor is defective.
If the monitor for the catalytic converter is broken, the exhaust pipes will let out more dangerous pollutants. It is, therefore, a serious offense to drive a vehicle with such a fault for a long time.
Monitor EVAP Not Ready, Effects #1: Catalyst Monitor Incomplete
This is one of the most common issues amongst automobile users after the “monitor EVAP not ready.” Despite being so common, many drivers are yet to grasp the causes of this problem and how to fix it. Sometimes, it may very well require you to stomach the cost to replace the purge valve with a new one.
The error message “catalyst monitor incomplete” comes to light due to certain conditions. Amongst all the possible causes of this error message, the following are usually the main culprits: Disconnected cell (s) or sensors, scan tool flashing, and simulator installations to fool the system. You might also notice OBD error codes such as PO441 or the P0441 code.
Monitor EVAP Not Ready, Effects #2: Disconnected Cells Or Sensors
When a cell or sensor is unplugged from the PCM, all of the saved memory from the different OBD II monitors is lost. When this happens, the system may not be able to start up all of the monitors, which makes them run the readiness checks.
Aside from this problem, most sensors lose the important data they’ve recorded, which stops the connection between the monitors and the PCM. At this point, it reports error codes of various kinds, further confusing non-experts.
Monitor EVAP Not Ready, Effects #3: Scan Tool Flashing
Some drivers may unconsciously reset the entire OBD II monitors using a scan tool. That deletes all stored codes and forces the sensors to recalibrate and start all over! Doing this, consciously or otherwise, not only takes effort, but it takes a lot of time for all OBD II monitors to complete various drive cycles and perform self-tests.
That may affect the EVAP System Monitor and result in the message “monitor EVAP not ready.”
Monitor EVAP Not Ready, Effects #4 Fooling The System Via A Simulator Installation
Impatient drivers would want to “fool” the car system with simulator installations. While many disadvantages lie with this, the inconsistency reported with these installations is something to ponder upon.
Some drivers install this simulation and try to fool a car system to report all OBD II monitors as “Ready“. These installations are often considered “Illegal,” with penalties awaiting offenders.
Most of the time, these installations damage the car’s internal wiring, which makes the displays stop working and gives the “catalyst monitor incomplete” error.
Monitor EVAP Not Ready, Effects #5: Fuel System Monitor Not Ready
The fuel system monitor is one among various OBD II readiness monitors. As the name indicates, it allows the PCM to assess how well the fuel management system is at reaching the ideal air-fuel ratio required in combustion chambers.
A continuous OBD II monitor continues to function during normal vehicle operations. The fuel system monitor works optimally when the EVAP system monitor is in good condition. Hence a problem with the EVAP system which displays the “monitor EVAP not ready,” can affect this monitor too.
When the fuel system monitor isn’t ready, the PCM can’t control the fuel injection, which leads to a cascade of additional issues. You may notice sluggish acceleration, stalling, or even cylinder misfires due to this problem. Based on the information in the fuel trim tables, the PCM controls how much fuel goes into the engine.
Fuel sensors indicate an oxygen-rich engine. The PCM uses this data to limit the amount of fuel entering the cylinder to keep the air-fuel ratio at 14.7:1 and vice versa during a closed-loop operation. Any alterations to this preset ratio lead to damage to engine components.
Incomplete Catalyst Monitors
The various signs that show an incomplete catalyst monitor include:
- Uneven acceleration or loss of engine power
- Bad exhaust odor
- The “check engine” light turns on
Monitor EVAP Not Ready: In Conclusion…
The evaporative emission control system (EVAP) is a very important system that prevents fuel vapor from escaping to the atmosphere when the engine is idle or running. “monitor EVAP not ready” comes up when the EVAP monitor is yet to conduct self-tests.
The message “monitor EVAP not ready” suggests that your vehicle may fail emission tests because the evaporative emission control system has not yet been enabled and the emission control systems are not detecting gasoline vapor leaks.
OBD drive cycles allow the powertrain control module (PCM) to evaluate the readiness of all monitors and perform self-tests. Drive cycles simulate regular vehicle functioning.
The number of drive cycles required to activate the OBD II monitors varies according to the year, model, and brand of the vehicle; however, the fundamental drive cycle count is almost the same for all vehicle types.
One of the several OBD II readiness monitors is the fuel system monitor. It allows the PCM to analyze how efficient the fuel control system is in producing the optimal air-fuel ratio required in the combustion chamber.
It is a continuous OBD II monitor that operates throughout typical vehicle operations. When the EVAP system monitor is in excellent working order, the fuel system monitor performs well. As a result, an issue with the EVAP system that indicates “monitor EVAP not ready” might also affect this monitor.
FAQs On EVAP Monitor Not Ready
What Does OBD Stand For
OBD stands for Onboard Diagnostics. It’s a system that helps diagnose faults within a car’s system.
How To Pass Emissions Readiness Test
All the OBD II readiness monitors must be READY to pass an emission test. We have explained why in this article.
How To Check If OBD Is Ready
A scan tool can help you check the various OBD II readiness monitors. How many readiness monitors can be incomplete? For older models, a maximum of one incomplete readiness monitor can get you a passing mark for the emissions test.
How To Complete Drive Cycle Without Driving
Right now, there is no way to complete a drive cycle without actually driving the car.