easyE300 Posted April 13, 2009 Share Posted April 13, 2009 Need help, check engine light with trac off light came on, can anyone tell me what this might be and would it be expensive to fix. Many thanks for your time Quote Link to comment Share on other sites More sharing options...
godzillatreat Posted April 14, 2009 Share Posted April 14, 2009 It's probably not a big deal. I just had that happen to my 99 ES300. I checked it out and it was the back o2 sensor. That is probably what it is P0420. It is the most common check engine light code to come up on any newer vehicle. I am going to buy an o2 simulator for my car. Replacing the unit which is not important (except for emissions) will be expensive. I love the environment, but the car burns clean. Take your car to Autozone or your local parts store. They will check out the code for free. When you get the code, check out this site to see what it is. www.obd-codes.com Quote Link to comment Share on other sites More sharing options...
capnfred Posted April 18, 2009 Share Posted April 18, 2009 godzillatreat, if you use an o2 sim, what will happen if there really is a problem with the engine,,,,does not the o2 sensor tell the ecu whether or not the engine is lean or rich... I understand using a sim if you bypass or remove the cat... but doesn't the puter need the o2 sensor input to determine the mixture... correct me if i am wrong... thanks... capn Quote Link to comment Share on other sites More sharing options...
stcist2 Posted April 18, 2009 Share Posted April 18, 2009 actually the rear 02 sensor is just reporting the efficiency of the catalytic converter(s)..actualy has no affect on performance or fuel mixture...that is if there are three or more sensors(V6)...if it is pre cat then yes it will affect the affiliated bank in which it is in-line with..I hope I'm not confusing anyone...just trying to help Quote Link to comment Share on other sites More sharing options...
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