Why is my 2014 Seat diesel's engine warning light illuminated?

Q. The engine management warning light is illuminated on my 2014 Seat diesel and the stop/start system isn’t working. Could it be diesel particulate filter (DPF) trouble or a VW emissions-fixing issue?
TG, Derby

A. The DPF has its own warning light, so it’s not that, plus you’d have seen a drop in performance. Your description points to a fault with the temperature sensor in the exhaust that tells the engine management system whether the engine is hot or cold.

Browse NEW or USED cars for sale on driving.co.uk

The stop/start system will work only with a hot engine and, as the sensor has failed, it has defaulted to the “cold” setting. You can check if your car has been affected by the VW scandal at http://www.seat.co.uk/owners/diesel-engines/vin-number.html

INSPECTOR GADGET
Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory — read more from Dave here.

GOT A PROBLEM?
Email your question to carclinic@sunday-times.co.uk or write to Car Clinic, Driving, The Sunday Times, 1 London Bridge Street, London, SE1 9GF, with a daytime phone number,
your address and as much detail about your car as possible. We can’t reply in person, so don’t send original documents or SAEs. Advice is given without legal responsibility.