6E1-54 DRIVEABILITY AND EMISSIONS
DTC MODES
There are 2 options available in the Scan Tool DTC
mode to display the enhanced information available.
After selecting DTC, the following menu appears:
• DTC Info
• Clear DTC Info
The following is a brief description of each of the sub
menus in DTC Info and Specific DTC. The order in
which they appear here is alphabetical and not
necessarily the way they will appear on the Scan Tool.
DTC Information Mode
Use the DTC info mode to search for a stored DTC
Refer to “Diagnostic Trouble Codes” list.
Clear DTC Information
The command for clearing DTC’s performs a
complete reset of the ECM.
PRIMARY SYSTEM-BASED
DIAGNOSTICS
PRIMARY SYSTEM-BASED
DIAGNOSTICS
There are primary system-based diagnostics which
evaluate system operation and its effect on vehicle
emissions. The primary system-based diagnostics are
listed below with a brief description of the diagnostic
function:
FUEL CONTROL HEATED OXYGEN
SENSORS (IF APPLICABLE)
The main function of the fuel control heated oxygen
sensors is to provide the control module with exhaust
stream oxygen content information to allow proper
fueling and maintain emissions within mandated
levels. After it reaches operating temperature, the
sensor will generate a voltage, inversely proportional
to the amount of oxygen present in the exhaust gases.
The control module uses the signal voltage from the
fuel control heated oxygen sensors while in “Closed
Loop” to adjust fuel injector pulse width. While in
“Closed Loop” , the ECM can adjust fuel delivery to
maintain an air/fuel ratio which allows the best
combination of emission control and driveability. The
fuel control heated oxygen sensors are also used to
determine catalyst efficiency.
HO2S HEATER
Heated oxygen sensors are used to minimize the
amount of time required for “Closed Loop” fuel control
to begin operation and to allow accurate catalyst
monitoring. The oxygen sensor heater greatly
decreases the amount of time required for fuel control
sensor (HO2S) to become active.
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