Without CONSULT

OVERALL FUNCTION CHECK
Instead of performing DIAGNOSTIC TROUBLE CODE (DTC) DETECTING CONDITION, the following method can be used for checking the three way catalyst function. (The "NG" of the OVERALL FUNCTION CHECK means the same as the DTC detection.
1) Start engine and warm it up sufficiently.




2) Set voltmeters probes between Engine Control Module (ECM) terminals 50 [front heated oxygen sensor (right bank) signal], 51 [front heated oxygen sensor (left bank) signal] and 25 (engine ground), and ECM terminals 56 (rear heated oxygen sensor signal) and 25 (engine ground).
3) Keep engine speed at 2,000 rpm constant under no load.
4) Make sure that the voltage switching frequency (high & low) between ECM terminals 56 and 25 is considerably less than that of ECM terminals 50 and 25, or 51 and 25.

^ Switching frequency ratio =
Rear heated oxygen sensor voltage switching frequency

^ Front heated oxygen sensor voltage switching frequency
This ratio should be less than 1/2

If the ratio is greater than 0.5, it means three way catalyst does not operate properly.

NOTE: If the voltage at terminal 50 or 51 does not switch periodically more than 5 times for 10 seconds at step 3, perform TROUBLE DIAGNOSIS FOR DTC 53 or 33 first.
^ For DTC 53, refer to Front Heated Oxygen Sensor (Right Bank).

^ For DTC 33, refer to Front Heated Oxygen Sensor (Left Bank).