P0128 2 weeks after replacing temp sensor

[JonathanLondon]

I would go back to the local independent garage much cheaper on your wallet.

But as they have supplied and fitted the part it should be down to them & their warranty (If the sensor is faulty).

Rusty, many thanks for your advice.  I actually contacted my local-ish Vauxhall dealership yesterday.  They want £99 to run diagnostics before they can tell me how much it will cost to repair.  And they can fit me in for the pick-up/drop-off service in October, or offer me a loan car in September.

Then I spoke to the local independent who are a short walk away who will look at the car tomorrow.  No contest.   The original repair there was £110 all in. They think it's unlikely to be the sensor again.  We'll wait and see.  (Previously the same Vauxhall dealership sent them the wrong part, and then it took a week to send the right part as they were merging their parts depot with Peugeot Citroen - happy days!)

If it's not the sensor, any thoughts on what else it is likely to be?

Thanks
Jonathan.