UK-POLOS.NET - THE VW Polo Forum

This Polo has its ABS light on all the time. It came on suddenly and permanently. The local garage has tried to interrogate but their scanner is unable to get to the ABS side of things. They insist that they would usually always be able to get full access to all aspects of a Polo via their unit, so they are convinced that this particular car is at fault.

Question: Does anyone have experience of this kind of non-communication? Is the garage mistaken, in that their computer is limited in its access and a main dealer would be able to identify the fault with proprietary equipment (or someone with the "right" scanner)

The car has been remapped by a previous owner to significantly increase the power

If it seems unlikely that ANY scanner could get in, would the ECU need replacing?

Is it worth checking the function of each of the wheel rotation sensors? I found a helpful Youtube vid (in Spanish) which showed how the voltages at a working sensor change with wheel position as the Hall effect device is activated. I have done one wheel like this and the readings look OK. Is it worth checking the others?

Finally, even if I happen to find a bad sensor and replace it, will the fault (light) still have to be cleared by computer - in which case I'm stuffed - or will it self clear, like when the pulses are present again after driving it a little?

Thanks,
Titus

Just because there is no communication doesn’t mean a failed ECU it could be a power or earth issue

A good techs next step would be to check all power and earth connections to the control unit,
You have to rule out that first before condemning a control unit.

Any other control units have a fault code?

Turned out to be a wheel sensor. I replaced the ABS pump/control module which did not kill the light, nor did it get rid of the 'no comms' problem. I had to break into each abs sensor connector to do static voltage checks (alternately 1.06v, 0.5v on a good sensor) to find the faulty one. Replaced it, light now off.

Glad you figured this out now , it’s always good to have a reply when a fix is successful