Skoda Octavia Elegance TDI 2 litre year 2008
I've posted before - so to recap: starting mid November the external temperature intermittently reads far too low - down to about -18 C when the actual temperature is nearer +10 C. The indicated value varies apparently randomly. It can read sensibly for a few days at a time.
Local garage replaced the sensor - no better.
With sensor disconnected indicated temperature shows --.- and the radiator cooling fans run at full speed.
Multimeter across sensor at room temperature (18 deg) shows 945 ohms (same both directions). Put sensor in freezer for 10 minutes - now measures 2.7k ohm. This is consistent with:
Connected a 470-ohm resistor across the contacts. Dashboard display shows about -8 C; so fault seems to be with wiring or control unit rather than the sensor.
I followed the wiring. The sensor is adjacent to the left foglamp. The wires from the sensor enter a thin corrugated plastic tube for about 6 inches, then this tube joins other wires from the foglamp and horn, and these three bundles of wire enter a larger protective plastic tube which goes vertically upwards a few inches where it is fixed to the metalwork near the back of the left headlamp. Here a thick brown wire from an earth point enters the bundle together with more bundles of thin wire. The bundle then runs under the air filter and fuse-box towards the bulkhead in front of the passenger seat.
This bundle looks clean and undamaged - where I can see it. There are no connectors in-line.
But at some point there must be a connector where it enters the control unit. Can anybody explain where this is, and how I would get to it to check for corrosion?
Is this control unit replaceable?