The S1 has two temperature senders: brown (sends to ECU), blue (sends to dash). The blue temperature sender is notoriously unreliable and often fails, resulting in temperature readings approx 10°C lower than reality. The blue sender is also a "single wire" type which is affected by electrical load. In most cases, a 1°C rise in temperature can be seen when turning on each item of electrical equipment, e.g. headlights, heater fan, windscreen wipers.
The S2 (Rover engine) has a single (black) temperature sender for both ECU and dash.
The S2 (Toyota engine) has ???
|Car||Sensor||Rover No||Unipart No||Other No|
|Elise S1||Brown||MEK100060||GTR 313 / 185||Elise Parts|
|Elise S1||Blue||YCB100420||GTR 316||Elise Parts|