How does one get the catalist monitor to run. 1999 Toyota 4 Runner failed emissions for cat failure. I replaced O2 sensor and front cat.No codes have come back,but cat monitor will not run. All other monitors have run. One problem veh does have, fuel gauge does'nt work reads full all the time any help would be app.
Where are you located? Does your 4Runner have a 4 cylinder or V6 engine?
The catalyst is monitored by the #2 O2 sensor circuit, which uses 2-trip detection logic. After clearing trouble codes, the electronic control module (ECM) has to see 2 consecutive trips without any faults from any sensors to be in "ready" mode. There are specific parameters, like a certain road speed, distance traveled, transmission gears used, coolant temperature, O2 sensors warmed up, etc. that must be met for a drive cycle to be counted by the ECM as a "trip."
The information is listed in Toyota TSB EG003-02 "Readiness Monitor Drive Patterns (Revised). Here is a link to a site with the TSB:
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