Quote:
Originally Posted by Rockit
Thanks so MUCH "Q" any idea hw many starts it takes to clear now fixed?
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It's not about "starts"...as mentioned above...the OBD II FTP (federal test protocol) has an established "drive cycle" where monitors are tested (see the chart in post above). Some of the monitors require two test because they monitor hot and cold situations...so following the outlined FTP drive cycle...may not clear all of the test monitors the first time if the monitor requires a "hot" and "cold" reading. It may occur in another drive cycle. Try to define a driving route/course that will allow you to accomplish the requirements for meeting the tests as outlined on the top half of the FTP drive cycle chart above.
OBD2 Readiness Monitors Explained
The purpose of readiness monitors is to self-test the car’s emission control systems. The monitors are also known as Emissions Monitors. Like the name indicates, they observe the performance of car’s emission related systems.
Cars may perform up to 11 system tests or routines. These tests are so called readiness monitors. The output of readiness monitors tell you whether the car’s computer has completed the tests successfully.
Readiness Monitor types
There are two different types of readiness monitors: continuous and non-continuous. Continuous monitors are different in design from the non-continuous ones. Continuous monitors are being constantly tested and evaluated while the engine is running. The non-continuous monitors need certain conditions to be met before a test can be completed.
The conditions necessary to run the non-continuous self-diagnostic tests vary. Some monitors require that the car follows a predefined drive cycle routine. Some require two drive cycles because of the need for a cool down and warm up periods between. Each emission monitor can have different requirements for the conditions.
Previously, the OBD2 standard (SAE J1979) categorized each defined monitor as either one. In the latest standard edition, this definite allocation is no longer present for all of them. Thus, OBD Auto Doctor doesn’t follow the categorization anymore either.
Continuous or Non-continuous Monitors
These monitors can be of either type. It’s up to the manufacturer to decide.
- Misfire
- Fuel System
- Comprehensive Component
- Non-Continuous Monitors
Non-continuous monitors are different for spark ignition cars (gasoline engines) and compression ignition cars (diesel engines).
- Spark ignition vehicles (Gas)
- Catalyst (CAT)
- Heated Catalyst
- Evaporative (EVAP) System
- Secondary Air System
- Oxygen (O2) Sensor
- Oxygen Sensor Heater
- EGR (Exhaust Gas Recirculation) and/or VVT System
- Compression ignition vehicles (Diesel)
- NMHC Catalyst
- NOx/SCR Aftertreatment
- Boost Pressure
- Exhaust Gas Sensor
- PM Filter
- EGR and/or VVT System
Monitoring cycles
Traditionally, the only monitor status was the status since the diagnostic trouble codes were cleared. This readiness monitor status is mandatory for all OBD2 compliant vehicles.
As the OBD2 has evolved, newer vehicles can now report emission monitor status also for the current driving cycle. These monitors start from the beginning every time when the monitoring cycle begins. Older cars might not support this feature.
Monitor status
Readiness monitor test result yields the monitor status. Each readiness monitor will have its own output status. The completion status can be:
Complete or ready meaning that the test has been completed. It means that the OBD-II system has checked this emissions control system and it has passed the test.
Incomplete or not ready meaning the test is not completed. It means that the OBD2 system has not been able to run this routine or it has failed.
Disabled meaning that the test has been disabled for the rest of this monitoring cycle. A monitor can be disabled when there is no easy way for the driver to operate the vehicle to allow the monitor to run. For example, the ambient air temperature might be too low or too high.