ecu temp sensor is screwed directly into the engine, its got 2 pins on and is white (well it'll be yellowy brown by now, but you get the idea

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replace it when the engine is proper stone cold, pop the header tank cap off then refit to release any pressure left in the system as its in a coolant channel, you'll loose a bit of coolant but if you're quick it wont be a lot.
lambda just disconnect the plug and tie it securly out of the way, see if the problem still occurs. if its solved then chances are its the lambda you need to replace, which isnt uncommon on these cars as they do wear out
