Auris 2016 - Beeping when ignition turned on AND when braking and coming to rest - also disables fron parking sensors

[Boughton Auris]

This is intermittent. Weird. Long beep and 1, 3 or 5 short beeps.Occurs when ignition is first switced on and when braking and car is almost stopped and coming to rest. In this "beeping" mode, from parking sensors are disabled.  Any clues anyone? Thanks

[Gerg]

I've not had anything similar happen, but would an intermittantly defective front parking sensor not give these symptoms?  On some factory fitted sensors, a detected fault can cause all the sensors to be disabled by the controller.

If the car is under warranty then a dealer might help, but at a Toyota dealer there will probably be a 'diagnostic charge' of 1/2 an hours labour or so, which you'll get returned only if the fault is accepted as a warranty claim.  But the warranty route can be barred by the garage saying that a defective sensor is caused by 'parking damage' - not necessarily you, someone else could have nudged the car whilst it was parked up, damaging the sensor - this is very difficult to disprove! 

I would expect the Toyota dealer diagnostic tool (called 'Techstream', fwiw), to be able to detect which sensor, or if the controller itself, is at fault.  But again, a charge will likely be made for doing that investigation, even though it is a quick job to 'plug the car in'.  The dealer will work in time measures of 1/2 an hour, or with a minimum default charge, I suspect.

On other, non-Toyota parking sensors, I have had some success by spraying WD40 momentarily onto the front of the sensor, and then wiping the excess off a second or so later.  The theory being that, by displacing some deeply ingrained water that has penetrated the circular sensor cavity (which is filled with soft rubber, I think), then allows the sensor to work normally again. Regardless of the theory, I've had this sometimes work for up to several years, but that's on rear sensors, which don't get struck by rain in the same way as fronts do on a moving car!

If one sensor is intermittently disconnecting/dying, then to find which one it might be, you can place the tip of your finger nail onto the centre of any sensor when it is actively detecting.  A 'normal' sensor will have a regularly occuring (once a second?) tingling vibration evident, a dead or dying one will have nothing.  It appears that, in your situation, the controller will likely shut the sensors down before you get a chance to try this when they are failing.

I would guess a new sensor is costing around £140 plus fitting, plus colour matching - assuming this is a Toyota fitted feature, not an aftermarket one.  If it is a parking sensor controller problem (unlikely), then you can expect to be paying the bill for the rest of your natural life.

I'm also reckoning here that this  is  a parking sensor problem!  Others may have alternative ideas.