MONITOR DESCRIPTION The ECM uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency. The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst informat
DIAGNOSIS SYSTEM CHECK DLC3 (a) Check the DLC3. Click here INSPECT AUXILIARY BATTERY VOLTAGE (a) Measure the auxiliary battery voltage with the power switch off. Standard voltage: 11 to 14 V If the voltage is below 11 V, recharge or replace the auxiliary battery.