I have a kia shuma 1.8 gsx 1999. The engine is misfiring when hot. The engine warning liht is constantly on now. No-one in my area has a diagnostic chip for this car. I have changed the lambda sensor and plugs with no change. This happened suddenly after putting petrol in one day. Any ideas?
Without the trouble code, speculating is not going to work. There are so many components that can cause the CEL to indicate and if you start replacing things without finding out the cause, it is going to waste a lot of time and money.