So I stuck new lambda sensors in my Rangie and sure enough they made sod all difference. It would appear that the lambda sensor heaters aren't being grounded by the ECU to turn them on.
Are there any funny situations where the ECU wouldn't just enable the sensor heaters?
If it's running in open loop, it might not power them?
Surely if they're not powered in open loop they will never heat up enough to start working and prevent it going into closed loop?
They should heat up enough to start working just from the exhaust gases when given some welly, plenty of earlier injected cars only had one or two wire sensors. Is this just on gas or on petrol too?
It's on both gas and petrol. Previously they would start to switch quite happily about a minute after starting from cold.