I'm new to this so please be kind to me if I make mistakes. I have a 1999 1.8 Zafira which has running problems. It seems to drive for a bit and lose power over and over again. I have had the car in the garage today and they have read the codes on their machine as PO135 02 sensor heating voltage low and P0505 idle air control voltage high. I have replaced already the air flow meter and egr valve with new parts. I have also changed the lamber sensor at the front. Obviously the orange engine light is on all the time. The car does start easily and idles fine. I just thought I would give you guys a go before I call in an Auto Electrician. Just to let you know that I am used to working on mk3 cavaliers and astra mk3s but thought I would get something a bit more up to date. Any help would be hugely appreciated. Thank you in advance for any help.