2001 Camry Sdn 4cyl auto 112000 miles

rcssr45rcssr45 Member Posts: 2
edited December 2016 in Toyota
After replacing the battery the ECM will not reset. Drove almost 1000 miles over a short period so it could 'learn' but no reset. Is the ECM bad, slow or is there something else I can do?


  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Not sure what you mean by "reset"? If the ECM wasn't working the car wouldn't run.

  • rcssr45rcssr45 Member Posts: 2
    Car starts runs (obviously) all good, no check engine light. Hooked to a scanner (would be done by DMV for inspection) it shows the EVAC and CAT "did not reset" Toyota said that upon a battery disconnect just driving the car for a few days/miles would reset everything but it doesn't. Car runs perfectly.???
  • thecardoc3thecardoc3 Member Posts: 5,727
    The EVAP, and CAT references would be the evaporative emissions system and catalytic convertor monitors of which at least one of them will have to complete for you to be ready for your emissions test. This really is what OBDII is all about.

    When one or more monitors won't complete the first thing that needs to be ruled out is if something is blocking them from running. Common blocking conditions are ambient conditions. There are a lot of systems that won't run the evaporative monitor if the ambient temperature is above 86f or below 40f. Some tests can be blocked if the engine doesn't reach a normal operating temperature range. So we might have to check to see if the thermostat is stuck open causing the engine to be too cold. Similarly, an overheating engine could also block some monitors from completing.

    Things can get a little more complicated from here if those initial checks don't reveal the problem. If the fuel control system is working too hard to control the engine which would be seen by the long and short term fuel trims making a large correction, the car could run fine, but monitors not complete. The reason for this is that the engineers never want to run a test and have the car either pass or fail a test if they cannot be 100% certain that the results of the test are accurate.

    The Toyota drive cycle needs to see the car cruise on the highway at a steady speed for as much as twenty minutes. The car will run the O2 sensor tests, which confirms that they are working correctly, and then it runs the catalyst test. The evaporative monitor should also run while on the road.

    You may have to get a tech to drive this and monitor the system with a scan tool to confirm whether or not if anything is in fact blocking the tests from running.
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