Traction light

The traction control light on my 2012 Kia Ceed 1.6 diesel comes on at exactly 47mph; the light goes off outside of this speed range. I’ve read the codes with an Autel MOT PRO V6.1 and there is a historic code: ‘CL520 clutch switch error’. There are no driveability problems when the light is on.

I also have another problem which is that the car drives well, but occasionally suffers from a hesitation. It feels as if your foot has slipped of the accelerator. It is also sometimes difficult to start. The fuel filter has been changed and injector cleaner additive put into the fuel tank, to no avail. For this fault, would it be a good idea to read the fuel pressure on the live data?

There is a possibility that the two problems are related. When the traction control comes on it will reduce the power to the engine. However, as you say there are no driveability problems when the traction control light comes on, this may not be the case.

The code referencing the clutch switch error may not be related and could just be a historic code. The best way to check if this is a problem would be to clear the code and see if it returns. If it does, the clutch pedal switch should be checked. The error occurs when the engine control module (ECM) does not detect the clutch operation at the appropriate times. The code number for this error should be ‘P0704’.

Provided no problems are found with the clutch pedal switch, the most likely source of the problem is a wheel speed sensor. These are incorporated into the ABS and traction control systems. The sensor detects the speed of each wheel and sends the information to the ECM. Some systems can be sensitive and can be upset if the tyre pressures are incorrect or the tyres are unevenly worn.

After checking the sensors are clean and in place, use your Autel MOT PRO V6.1 to track the operation of the ABS sensors while driving, to ensure they are all supplying the same reading. If one of the sensors is out of balance, I would check the connections and the pick-up. If no fault can be found here, I would suspect the sensor has failed.

The hesitation problem may be a separate issue and, as you suggest, using the live data to check the fuel pressure stability while driving would help to highlight any issues.