MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-167
.
CIRCUIT OPERATION
•
A voltage corresponding to the oxygen concen-
tration in the exhaust gas is sent to the ECM (ter-
minal 74) <M/T> or PCM (terminal 74) <A/T>
from the output terminal (terminal 4) of the right
bank heated oxygen sensor (rear).
•
Terminal 2 of the right bank heated oxygen sen-
sor (rear) is grounded with ECM (terminal 49)
<M/T> or PCM (terminal 57) <A/T>.
.
TECHNICAL DESCRIPTION
•
The output signal of the right bank heated oxygen
sensor (front) is compensated by the output sig-
nal of the right bank heated oxygen sensor (rear).
•
The ECM <M/T> or PCM <A/T> checks for an
open circuit in the right bank heated oxygen sen-
sor (rear) output line.
.
DTC SET CONDITIONS
Check Conditions
•
3 minutes or more have passed since the starting
sequence was completed.
•
Right bank heated oxygen sensor (rear) signal
voltage has continued to be 0.15 volt or lower.
•
Engine coolant temperature is higher than 76
°
C
(169
°
F).
•
Engine speed is higher than 1,200 r/min.
•
Volumetric efficiency is higher than 25 percent.
•
Volume air flow sensor output frequency is 75 Hz
or more.
•
At least 20 seconds have passed since fuel shut
off control was canceled.
•
The right bank heated oxygen sensor (front) out-
puts 0.5 volts or more.
•
After the ignition switch is turned ON, the
changes in the output voltage of the right bank
heated oxygen sensor (rear) is lower than 0.078
volt.
•
Monitoring time: 10 seconds.
Judgement Criteria
•
Making the air/fuel ratio 15 percent for 10 sec-
onds richer does not result in raising the heated
oxygen sensor (rear) output voltage beyond 0.15
volt.
•
The ECM <M/T> or PCM <A/T> monitors for this
condition once during the drive cycle.
.
TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )
•
Right bank heated oxygen sensor (rear) failed.
•
Short circuit in right bank heated oxygen sensor
(rear) output line.
•
ECM failed. <M/T>
•
PCM failed. <A/T>
DIAGNOSIS
Required Special Tools:
•
MB991502: Scan Tool (MUT-II)
•
MB991316: Test Harness Set
AK000225
CONNECTORS : C-58, C-62<M/T>,
C-55, C-59<A/T>
C-55
C-58
PCM<A/T>
ECM<M/T>
AK
C-59
C-62