Constant beep sound in reverse gear

[Volvo90]

Hi, this is my first Volvo (XC90) and first post. When I put the gear into reverse it immediately beeps constantly. I had it check and was told sensor 2 was at fault but sometimes the rear parking sensors work fine.

I did the sensor test, placing gear in reverse and listened for ticking sound and all sensors are working. Can someone advise before I buy a new sensor and labour costs?

[owenfackrell]

Check that the module is plugged in properly. Ours did this intermittently when we first got it and the plug was slightly loose. To find it you will need to access where the jack is and then remove the triangle of carpet to the passenger side. The module is located next to the wheel arch.

[Baxlin]

Daft question, but are the sensors definitely clean?

[Volvo90]

Hi, thank you for your response I pulled out the upholstery as instructed the module I believe was attached by velcro I checked the connection all seemed fine. It is off/on it doesn't work and then the sensor work as normal then vice versa.

Happy Easter

[Volvo90]

Not daft I take it you mean outwardly...the car is washed regularly so I guess the answer is yes they are clean. Not sure if water getting in effects it? Shouldn't do.

Happy Easter

[gmonag]

The DTC indicates a fault with no. 2 sensor, so it should be replaced. However you should check the harness for shorts after you remove the bumper and before you swap the parts, as this can give the same indication.

[SwissXC90]

Originally Posted by Volvo90

Hi, this is my first Volvo (XC90) and first post. When I put the gear into reverse it immediately beeps constantly. I had it check and was told sensor 2 was at fault but sometimes the rear parking sensors work fine.

I did the sensor test, placing gear in reverse and listened for ticking sound and all sensors are working. Can someone advise before I buy a new sensor and labour costs?

The XC90 sensors can suffer from water in the bumper internal cabling or in the sensor housing.

My XC90 will occassionally sound a continuous tone when it has been raining and I have been driving in the rain. And my system is kept spotlessly clean.

Water can get into the sensor housing through capillary action and cause the transmitted pulse to be dampened and picked up by the sensor, making it thing an object is in the way.
Volvo had a service bulletin regarding the water ingress problem and how to prevent water getting into the housing by sealing the housing. Dismantling required.

So how do you know if yours is so affected?
Wait for a dry spell and see how the system performs when everything is properly dry. It OK then it is a water ingress problem.

[Volvo90]

Thanks for that but I think the problem has been resolved since trying what was advised by Owen Fackrell. Removed the upholstery the module was a bit loose. I re-applied it to the velcro and so far so good!

[Volvo90]

Originally Posted by owenfackrell

Check that the module is plugged in properly. Ours did this intermittently when we first got it and the plug was slightly loose. To find it you will need to access where the jack is and then remove the triangle of carpet to the passenger side. The module is located next to the wheel arch.

Hey Owen, since I removed the upholstery and re-applied the module to the velcro so far it has worked fine and if that was the reason it being loose was immediately sending a signal once in reverse that I was touching distance. Saved me some parts and labour cost.

Much appreciated

[owenfackrell]

No problem. Hope it has worked for you. Mine has been fine for the last few years since I put mine back in place.