DSTC failed - bouncy brake boost pressure sensor XC90 2003

[npexcept]

Hello people!

Literally from one day to the other I'm getting this DSTC/ABS error (BCM-0139 Pressure build-up valve, power brake booster. Signal outside its permitted range).
Hooked up VIDA and read out the sensor values for the pressure sensor 1 and 2.
With the key in pos II (engine off) and not pressing the brake pedal, one of the sensors jumps around quite a bit;

EDIT: Fault found! Read about it here: viewtopic.php?t=103915

sensor 1 bounces between -1.12 bar and -1.55 bar. I suspect thats the reason for the BCM-0139 error. (Edit: this was a wrong assumption, culprit was a corroded BCM connector)
Sensor 2 stays mostly on -0.7 bar.

I did a new sensor calibration with VIDA and the values stay together pretty much all the time when pressing the brake pedals.

35b.jpg (155.39 KiB) Viewed 2547 times

Could anyone confirm that this "bouncing" triggers the error?
Bat voltage is OK and bouncing persists also with engine in idle.
I plan on replacing sensor 1 now. Shoud I replace sensor 2 also (with its little bouncing)?

for reference; sensor 1 and 2 are marked as "22"

22.png (189.11 KiB) Viewed 2547 times

Thank you!

[ggleavitt]

Values match P1 and P2, think offset is reasonable. I might check the integrity of your electrical connections given the jumpiness of the sensor 1 output with the brake pedal untouched. If you do end up replacing one brake booster pressure switch, replace them both.

I get this message sporadically. Volvo sensors are pretty pricey, I have a pair of Pro-Parts 28433669 that I purchased last year which I'll use to replace when I get around to it (Ocean Race).

Mentions of BCM-0139 in this link- viewtopic.php?t=91350