My parking sensors, front and rear, have both stopped working. My fault code is B1B42 (Front Left Inner Sensor). When I start the car there I a long beep, similar to that heard when the sensors are activated as when selecting reverse; the beep stops and, if I then select reverse, the button on the centre console will flash but nothing more - no sound/ beeps. If I select Drive and press the button it does the same - no sound/ beeps.

I have read elsewhere on here that a failure at one end should not affect the other. I have also checked the fuse in the boot which is fine.

I haven't been wading, but it did stop during some bad weather leading me to suspect water ingress as suggested, again, elsewhere on this site.

If anyone has experienced a similar problem or has any idea what it could be, I would love to know about it.

Thanks in advance.[/i]

one on front went on mine which disabled both front and rear
fault code said centre rt but after taking bumper off turned out to be
outside left which did not need bumper removal

That's interesting. I thought the bumper had to come off to swap out any of the front sensors. How difficult was it to remove the bumper?

Park Assist module requires a CAN reset, if you don't have a diagnostic tool to do this then try a hard reset assuming you've replaced the faulty sensor or rectified the short circuit (water ingress).
PAM sometimes need a CAN reset once a fault is registered particularly if it was a short circuit.

Front outboard sensors are accessible from inside each wheel arch liner inspection hatch (or through fog light bezels, if you've got small hands ), including the main harness plug on passenger side. Drivers side has washer bottle in the way so possibly the fog light bezel on that side is a better bet. Inboards I think is bumper off or possibly could get access by removing headlight unit but not sure about that.

If you have "bumper styling cover" as I do it's bumper off. MY15
Tyre Pressure Monitoring System (TPMS)
Surround Camera System
InControl Apps soon to be replaced with CarPlay (WIP)
Meridian Premium Surround Sound
Digital Audio Broadcast
Timed Climate
Cruise ECO Data
Follow Me Home Reverse
Extra Features Menu
Picture In Motion
4x4i screen (WIP)
Digital Broadcast TV
Meridian Rear Media with WIFI
Factory Powered Tailgate
Blind Spot Monitoring (BSM)
Reverse Cross Traffic Alert (RCTA)
Electrochromatic Wing Mirrors (WIP)

there are videos on here and you tube re bumper removal
time depends on your age & flexibility

I have found the problem with the sensors.

I took the bumper off to carry out some work on the turbo and hoses etc, and found the multi plug connector, which connects the car to everything attached to the front bumper, had become 'unhooked' from its mount on the inside of the passenger side wheel well. This caused it to fall down and rest at the base of the front bumper behind the wheel arch liner. I'm guessing that water had manged to get into the plug and short out the sensors.

As the bumper was off, I decided to apply silicon around the sensor connections on the bumper itself and around the multi plug before re-attaching the latter and securing with trusty cable ties.

I also found this which may be useful to someone -

Did you need to take her in to be reset??

No. I have a nanocom diagnostic so was able to do myself.