Ernie50 Posted April 30, 2004 Share Posted April 30, 2004 any one has any idea what is p0420 engine check light mean ???? Quote Link to comment Share on other sites More sharing options...
jsmith8918 Posted May 1, 2004 Share Posted May 1, 2004 This may not be exactly right for your application as it is actually in the manual for the Toyota, but it could serve as a starting point if nothing else: P0420: System detected: Catalyst System Efficiency Below Threshold Possible Trouble Areas: 1. 3-Way Cat. Converter Problem 2. Ophen/Short HO2S Circuit 3. HO2S Failure Hope this helps. Quote Link to comment Share on other sites More sharing options...
445187 Posted May 1, 2004 Share Posted May 1, 2004 this may sound silly, but check you gas cap & be sure that it is tight, if it isn't or the seal is worn, it could cause the check engine light to come on... Quote Link to comment Share on other sites More sharing options...
SKperformance Posted May 1, 2004 Share Posted May 1, 2004 If your cat is not functioning properly it is probably caused by something like carbon build up. What gas are you using? Also find a local motorvac or terra fuel place that does high pressure fuel injection cleaning. Quote Link to comment Share on other sites More sharing options...
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