Brake Failure Service Urgent message - Yaw Sensor Replaced

[stoatallyawesome]

On a 2000 V70 2.4 T Petrol.

First symptom was 'Brake Failure Service Urgent' message appearing one morning.

After a couple of months of digging and diagnosing, was traced to a faulty yaw sensor.

Our V70 has 2 - one under the drivers seat and one under the centre console.

I have replaced the one under the drivers seat and had the codes cleared and the yaw sensor error is no longer present.

The 'brake failure' message and light is still lit on the dashboard.

My question is - should the code being cleared extinguish the fault message and light or does this need a separate reset? Can it only be reset by Volvo?

I'm trying to work out if I've replaced the right yaw sensor as it seems unlikely that both have failed at once.

Thanks!

[Georgeandkira]

So you say there are no codes now? You're using a good quality reader, no?

I don't know if the "disconnect the battery" trick works on messages but might be worth a try because it's simple and costs nothing to do.

Are your brakes worn? Maybe the master cylinder's piston has bottomed out.

Also, there were ABS control module solder joint failures with your era car. E5 torx socket removes the controller from the ABS unit.
This leaves the car drivable. It just won't have ABS while removed.

[stoatallyawesome]

Thanks for your reply. I took it to a local garage for a quick code read and clear. I haven't got a machine myself as each time I go to the garage for a read and clear, I glean just a little extra info

Master cylinder, well its most likely the original and I have noticed that the brake take a lot of pressure to apply. Do you know of any other symptoms I could look for/test for a problem with the piston?

There were no other ABS errors in the fault codes but its worth investigating.

I did wonder about a battery disconnect, good idea, I'll give that a go.

[stoatallyawesome]

Just wanted to post the resolution to this issue.

After having the ABS sensor removed and serviced, the yaw sensor replaced and several hours of head scratching...

The problem was a faulty brake fluid fill level sensor.
Can't find a replacement as they are no longer manufacturer so simply disconnected and all warning lights extinguished.