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2020 S60 Parking Assist Sensors Malfunctioning After Rain

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Mike T. · rep 0 · May 24, 2:56 PM · 1 replies · solved · Question

Vehicle: 2020 Volvo S60 T5 Momentum

Hey everyone,

I'm having an issue with my 2020 Volvo S60 T5 Momentum. Lately, especially after it rains or after I've driven through some puddles, my parking assist sensors start acting up. I get a 'Service Parking Assist' message on the dashboard, and the sensors either don't detect anything when they should, or they go off constantly for no reason.

It's really frustrating because I rely on them for tight parking spots. Sometimes, after the car dries out completely, they'll work fine for a bit, but then the problem comes back with the next bit of wet weather. I've tried wiping them down, but it doesn't seem to make a difference.

Has anyone else experienced this with their S60 or another Volvo model? Is this a common issue, and what could be causing it? Any advice on what I can check myself before taking it to the dealer would be greatly appreciated. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 24, 2:56 PM

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ClearTheCode admin answer:

It sounds like you're dealing with a common problem related to moisture affecting your parking assist sensors. Here's a breakdown of what might be happening and what you can do:

  1. Inspect and Clean Sensors Thoroughly: Even if you've wiped them, give each sensor a good clean with a soft cloth and some mild soapy water. Sometimes, a thin film of dirt or road grime can interfere with their ultrasonic signals, and this becomes more pronounced when wet. Ensure there's no mud, ice, or debris lodged around the sensor housing.
  2. Check for Visible Damage: Carefully examine each parking sensor (located in your front and rear bumpers) for any cracks, dents, or signs of impact. Even minor damage can compromise their waterproof seal.
  3. Examine Wiring and Connectors: While more difficult without lifting the car, if you can safely access the back of the bumper, check for any visible signs of corrosion or damage to the wiring harnesses and connectors leading to the sensors. Moisture can get into these connections and cause intermittent faults. You might even try disconnecting and reconnecting them (if easily accessible) to ensure a good contact.

Common Causes for Parking Sensor Malfunctions (especially after rain):

  • Water Ingress: This is the most likely culprit. Water can get inside the sensor unit itself, or into the electrical connectors, causing short circuits or signal interference. As the car dries, the connection might temporarily restore.
  • Corrosion: Moisture can lead to corrosion on the sensor pins or wiring, leading to poor electrical contact.
  • Faulty Sensor: One or more individual sensors might be failing, and their internal components are more susceptible to moisture.
  • Wiring Harness Issues: Damaged or frayed wiring leading to the sensors can also cause intermittent problems.
  • Control Module Glitch: Less common, but sometimes the Parking Assist Module (PAM) or Body Control Module (BCM) can experience a temporary software glitch due to electrical fluctuations, which might be exacerbated by moisture.

When to See a Shop:

If the problem persists after you've thoroughly cleaned the sensors and visually inspected for damage, it's time to take your Volvo to a qualified service center or dealership. They have specialized diagnostic tools that can:

  • Read manufacturer-specific fault codes that a generic OBD-II scanner might miss. These codes can pinpoint which specific sensor is faulty or if there's an issue with the control module.
  • Perform advanced diagnostics to test the functionality of each sensor and the associated wiring.
  • Replace faulty sensors or repair damaged wiring/connectors. Ignoring persistent electrical issues can sometimes lead to more complex problems down the line.
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