DTC P0420, P0430 THREE WAY CATALYST FUNCTION
EC-1487
[VG33ER]
C
D
E
F
G
H
I
J
K
L
M
A
EC
7.
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 voltage switching frequency
B: Heated oxygen sensor 1 voltage switching frequency
This ratio should be less than 0.75.
If the ratio is greater than above, it means three way catalyst
(manifold) does not operate properly. Go to
EC-1488, "Diagnos-
tic Procedure"
.
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 diagnosis for DTC P0133, P0153 first. (See
EC-1384
.)
SEF442V