Overall Function Check
NCEC0242
Use this procedure to check the overall function of the three way
catalyst. During this check, a 1st trip DTC might not be confirmed.
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 62 (Heated
oxygen sensor 1 (front) signal), 63 (Heated oxygen sensor 2
(rear) 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 terminal 63 and engine ground is much less
than that of ECM terminal 62 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 three way catalyst
does not operate properly.
NOTE:
If the voltage at terminal 62 does not switch periodically more
than 5 times within 10 seconds at step 4, perform trouble
diagnosis for DTC P0133 first. (See EC-SR-163.)
Diagnostic Procedure
NCEC0243
SEF074X
1
CHECK EXHAUST SYSTEM
Visually check exhaust tubes and muffler for dent.
OK or NG
OK
©
GO TO 2.
NG
©
Repair or replace.
DTC P0420 THREE WAY CATALYST FUNCTION
SR20DE
Overall Function Check
EC-247