The ABS warning light has just come on (as I left the MOT station) and I have taken all the wheels off and checked the sensors. They all read about 1050Ohms and give out an AC ripple when I spin the hub, EXCEPT the off side rear which reads 2KOhms. Ive decided to change this sensor and wondered if I had to reset anythin once I had replaced the sensor or (if this was indeed the fault) will the light automatically go out. I put a 1020 Ohm resistor on to the wires of the rear sensor cable and turned on the ignition and rather hoped that this would fool the system into clearing the fault, but no...

Also can anyone recommend a diagnostic kit which I could use with my laptop.

Many thanks

Vcds is perfect for laptop use

When we changed one on my mates VRS I think there was a stored code which I just cleared with my Liquid gauge. Or you could clear it with VCDS or any VAG fault code scanner/clearer. If you fit a resistor it will still throw a code because it's expecting to get that "ripple" as the wheels turn, if it doesn't get that then it throws the code.

Thanks for the info. I was hoping that on its initial check it would only check resisitance and therefore not show a warning light until the wheels started rolling. Alas I was wrong.

I've just dropped off my daughter at brownies and the warning light went out for a while and then came back on again. I presume that this means that it is a marginal fault and that the light will turn itself off when the system is happy. Is this correct or do I need to reset fault codes or similar to turn off the warning light when I've fixed the fault?

I bought one of these for £19 from Amazon "U280 Car Scanner Reader OBD2 OBD 2 VW Audi SEAT SKODA diagnostic Fault Code Reader VAG" very useful and confirmed that the faulty abs sensor was the os rear. When I replaced the sensor the warning light remained on. I then cleared the code using the U280 and hey presto all is now well and the ABS light is off and stays off.

I'm told that a simialr but slightly different unit exists for the MK2 octavia. Its cheap easy to use and though not detailed, it is a great aid to diagnostics and clearing fault codes.