Thanks for the suggestions.
I checked the codes only after the engine light came on. I have cleared the code once before and it’s returned. I was hoping to identify where the sensor is plugged in, to then disconnect it and recheck the codes. I’ve cleared the code again this evening.
The problem developed shortly after a standard Revo remap was flashed onto the van. I put this entirely down to coincidence. The driving performance improved after the remap and I can’t distinguish any deterioration since the engine warning light has come on.
The van is a highline panel van. It’s covered 32000 miles.