Ok folks, my mate has a Corrolla Compressor, and this week spent a VERY large sum of money on a custom exhaust for it. Like, silly money! it's utter porn, cant wait to see it for myself. HOWEVER, in the midst of it the guy also inserted a decat as requested, but this seems to upset the lambda sensor and is causing the engine management light to come on. any suggestions for how to resolve this engine light coming on folks???? Phil.