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SEF441V
SEF442V
Overall Function Check
NGEC0742
Use this procedure to check the overall function of the warm-up
three way catalyst. During this check, a 1st trip DTC might not be
confirmed.
CAUTION:
Always drive vehicle at a safe speed.
Without CONSULT-II
1) Start engine and drive vehicle at a speed of more than 70 km/h
(43 MPH) for 2 consecutive minutes.
2) Stop vehicle with engine running.
3) Set voltmeters probes between ECM terminals 50 [heated oxy-
gen sensor 1 (front) (bank 1) signal], 51 [heated oxygen sen-
sor 1 (front) (bank 2) signal] and engine ground, and ECM ter-
minals 56 [heated oxygen sensor 2 (rear) (bank 1) signal], 57
[heated oxygen sensor 2 (rear) (bank 2) signal] and engine
ground.
4) Keep engine speed at 2,000 rpm constant under no load.
5) Make sure that the voltage switching frequency (high & low)
between ECM terminals 56 and engine ground, or 57 and
engine ground is very less than that of ECM terminals 50 and
engine ground, or 51 and engine ground.
Switching frequency ratio = A/B
A: Heated oxygen sensor 2 (rear) voltage switching fre-
quency
B: Heated oxygen sensor 1 (front) voltage switching fre-
quency
This ratio should be less than 0.75.
If the ratio is greater than above, it means warm-up three way
catalyst does not operate properly. Go to “Diagnostic
Procedure”, EC-955.
NOTE:
If the voltage at terminal 50 or 51 does not switch periodically more
than 5 times within 10 seconds at step 5, perform trouble diagno-
sis for “DTC P0133, P0153” first. (See EC-807.)
DTC P0420 (RIGHT BANK, -B1), P0430 (LEFT BANK, -B2)
THREE WAY CATALYST FUNCTION
VG33E
Overall Function Check
EC-954
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