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2022 XC60 B5 Start-Stop not engaging, occasional delayed start

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Mark S. · rep 0 · May 22, 5:12 AM · 1 replies · solved · Question

Vehicle: 2022 Volvo XC60 B5 R-Design

Hello Volvo community,

I'm reaching out about an issue with my 2022 Volvo XC60 B5 R-Design. For the past few weeks, the start-stop system has completely stopped working. It used to engage regularly, but now it never does, even on long drives when the engine is fully warmed up and all conditions seem right.

In addition to that, I've noticed a couple of times that the engine has a slightly delayed start, almost like it's cranking a bit longer than usual before firing up. There's no check engine light, but these two things together are making me a bit concerned.

Could these issues be related? Has anyone with a newer B5 engine experienced similar problems? What should I be looking for?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:12 AM

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ClearTheCode admin answer:

The issues you're describing with your 2022 Volvo XC60 B5 R-Design – specifically the non-functional start-stop system and occasional delayed starts – are often interconnected and point towards the vehicle's 12V battery or the mild-hybrid system's auxiliary battery.

Common Causes:

  1. 12V Battery Health: The primary 12V battery is crucial for starting the engine and powering all vehicle electronics. If it's weak or nearing the end of its life, the car's systems, including start-stop, will prioritize reliable starting over convenience features. The B5 engine's mild-hybrid system also relies on a healthy 12V battery.
  2. Auxiliary Battery (Mild-Hybrid System): The B5 engine utilizes a 48V mild-hybrid system, which includes an auxiliary battery (often a small lithium-ion unit) that assists with engine starting and powers the start-stop function. If this battery or its associated components (e.g., DC/DC converter) are faulty, the start-stop system will be disabled.
  3. Battery Management System (BMS) Issues: The BMS monitors battery health and decides when to enable or disable start-stop. A fault in the BMS or its sensors could incorrectly disable the system.
  4. Charging System Problems: While less likely without a warning light, issues with the alternator or voltage regulator could prevent proper battery charging.

When to See a Shop:

Even without a CEL, these symptoms warrant a professional diagnosis. A Volvo dealership or a shop with specialized diagnostic tools can accurately pinpoint the problem:

  1. Battery Load Test: They will test the health of both your primary 12V battery and, if accessible, the auxiliary mild-hybrid battery. A weak 12V battery is the most common culprit for start-stop issues.
  2. Diagnostic Scan: A comprehensive scan can reveal specific fault codes related to the battery management system, mild-hybrid system, or power delivery modules (e.g., P0A80 - Replace Hybrid Battery Pack, though less common for just start-stop).
  3. Software Check: Ensure all relevant control modules have the latest software updates.
  4. Charging System Inspection: Verify that the alternator and mild-hybrid charging components are functioning correctly.

Addressing battery health is critical for the proper operation of modern Volvos, especially those with mild-hybrid technology.

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