I have a vitz 2004 since 2008 and have been running it on CNG ever-since. Now the problem is that, it has never given the check engine indication consistently before. The light started appearing consistently around the time when my engine oil was due, so after the change of engine oil, oil and air filters, and even transmission oil the light stopped appearing for 4 days and I was relieved that the problem has been solved but for almost a week now its on consistently.
Now i know its a common problem with Vitz but as I said I never had this problem before.
Any specifics I should get checked because I dont wanna go to Toyota "Rip-off" Motors till something really is up.
P. S I am positive I dont see this light when the car is on petrol.
Any help? Advice?