Obd 2 Monitors - Innova 3100 Owner's Manual

Learning More

OBD 2 MONITORS

Misfire and fuel system faults require three trips with "similar
conditions" before the MIL is turned "Off." These are trips where
the engine load, RPM and temperature are similar to the
conditions present when the fault was first found.
After the MIL has been turned off, DTCs, Freeze Frame
data, and manufacturer-specific enhanced data stay in the
computer's memory. This data can only be retrieved by
using equipment such as a Scan Tool.
Erasing the DTCs from the computer's memory can also turn off
the MIL. See ERASING DIAGNOSTIC TROUBLE CODES (DTCs)
on page 20, before erasing codes from the computer's memory. If
a Code Reader or Scan Tool is used to erase the codes, Freeze
Frame data as well as other manufacturer-specific enhanced data
will also be erased.
OBD 2 MONITORS
To ensure the correct operation of the various emissions-related
components and systems, a diagnostic program was developed and
installed in the vehicle's on-board computer. The program has several
procedures and diagnostic strategies. Each procedure or diagnostic
strategy is made to monitor the operation of, and run diagnostic tests
on, a specific emissions-related component or system. These tests
ensure the system is running correctly and is within the
manufacturer's specifications. On OBD 2 systems, these procedures
and diagnostic strategies are called "Monitors."
Currently, a maximum of eleven Monitors are used in OBD 2
systems. Additional monitors may be added as a result of
Government regulations as the OBD 2 system grows and matures.
Not all vehicles use all eleven Monitors.
Monitor operation is either "Continuous" or "Non-Continuous,"
depending on the specific monitor.
Continuous Monitors
Three of these Monitors are designed to constantly monitor their
associated components and/or systems for proper operation.
Continuous Monitors run constantly when the engine is running. The
Continuous Monitors are:
1. Comprehensive Component Monitor (CCM)
2. Misfire Monitor
3. Fuel System Monitor
Non-Continuous Monitors
The other eight Monitors are "non-continuous" Monitors. "Non-
continuous" Monitors perform and complete their testing once per trip.
The "non-continuous" Monitors are:
38 OBD 2