SEF484Y
On Board Diagnosis Logic
NBEC0214
The ECM monitors the switching frequency ratio of heated oxygen
sensors 1 (front) and 2 (rear).
A warm-up three way catalyst with high oxygen storage capacity
will indicate a low switching frequency of rear heated oxygen sen-
sor. As oxygen storage capacity decreases, the rear heated oxy-
gen sensor switching frequency will increase.
When the frequency ratio of front and rear heated oxygen sensors
approaches a specified limit value, the warm-up three way catalyst
malfunction is diagnosed.
Malfunction is detected when warm-up three way catalyst does not
operate properly, warm-up three way catalyst does not have
enough oxygen storage capacity.
Possible Cause
NBEC0504
I
Warm-up three way catalyst
I
Exhaust tube
I
Intake air leaks
I
Injectors
I
Injector leaks
I
Spark plug
I
Improper ignition timing
GI
MA
EM
LC
FE
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0420 (RIGHT BANK, -B1), P0430 (LEFT BANK, -B2) THREE WAY
CATALYST FUNCTION
On Board Diagnosis Logic
EC-347