Unlocking the Secrets Delving into the Causes of Fuel System Monitor Unreadiness

The fuel system monitor allows the PCM to evaluate how close the fuel control system can regulate the fuel mixture in attempting to achieve an optimum air/fuel ... ... not the heater, and the secondary air system ans so on, Can't wait to go ... not to get ripped off and just look into getting the monitors ready. Back. Try to keep the fuel level above a quarter of a tank and below a full tank and drive the vehicle for around 50 miles or so after these steps are done and the ... For instance, the catalyst monitor will rely on the air fuel ratio sensor and oxygen sensor for it's test routine. If you check the air fuel ratio sensor test ... Its possible they are not fully passing, yet are not fully failing that monitor test. Sometimes it is not even the sensor itself, but a circuit related issue, ... Diagnostic scanner? IIRC, these trucks have Misfire, EVAP, O2, Heated O2, Catalyst, Fuel System, EGR/CMP and I can't remember the last monitor. Some codes can prevent the continuous monitor of Fuel System (runs at startup) should be ready unless some code prevents it. No O2, Evap or fuel codes per GAP ... This test is done automatically in the middle of the night, when it is not being driven, after the engine has fully cooled down, and it repeats ... I can have that one show not ready. Fuel system must show ready to pass smog.I have replaced the fuel cap, battery, fresh fuel multiple times, ... have the fuel tank between 30 and 70 percent full. some systems, especially the evap system, need to have a specific level of fuel in order for ...