MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE>
13A-30
SYSTEM READINESS TEST STATUS
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PURPOSE
The Readiness function (also referred to as I/M
Readiness or I/M Flags) indicates if a full diagnostic
check has been "Completed" (is "Ready") for each
non-continuous monitor. Enhanced I/M State Emis-
sion Programs will use the Readiness status (Codes)
to see if the vehicle is ready for OBD-II testing.
"Incomplete" (Not Ready) codes will be one of the
triggers for I/M failure.
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OVERVIEW
The PCM monitors the following main diagnosis
items and records whether the evaluation was com-
pleted or is incomplete. The Readiness Codes are
established for the I/M programs, thereby confirming
that the vehicles have not been tampered with by
erasing the diagnostic trouble code(s) (DTCs) before
I/M testing. The Readiness Codes and DTCs can be
reset by disconnecting the battery or by erasing the
codes with a scan tool MB991958 (MUT-III sub
assembly). For this reason, all the Readiness Codes
must be displayed "Complete" before I/ M testing.
When the monitors run and complete, the scan tool
MB991958 (MUT-III sub assembly) will display the
Readiness Codes as "Complete" (General Scan
Tools display as "Ready"). When the vehicle is oper-
ating normally and the OBD-II Drive Cycle is carried
out, the Readiness Codes will be set as "Complete"
on the first drive cycle. For DTCs requiring two drive
cycles to detect a fault, the second drive cycle is
required to set the Readiness Codes as "Complete"
if a fault is detected during the first drive cycle. If the
fault is still there after the second drive cycle, a DTC
will be set.
• Catalyst: P0421, P0431
• Evaporative system: P0442, P0455, P0456
• Heated oxygen sensor: P0130, P0131, P0132,
P0133, P0134, P0136, P0137, P0138, P0139,
P0150, P0151, P0152, P0153, P0154, P0156,
P0157, P0158, P0159
• Heated oxygen sensor heater: P0135, P0141,
P0155, P0161
• EGR system: P0401
After all the Readiness Codes are displayed as
"Complete", the technician is assured that any DTCs
related to the monitor will be displayed if the system
has a problem. That is why some State's I/M pro-
grams require the Readiness Code as "Complete"
before they check for DTCs.
NOTE: After a repair is made for a DTC, the techni-
cian should drive the OBD-II Drive Cycle checking
that the scan tool MB991958 (MUT-III Sub Assem-
bly) displays all the Readiness Codes as "Complete"