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Coolant Loss on my 2020 Audi Q5 Premium Plus

0

Kevin B. · rep 0 · May 22, 4:30 AM · 1 replies · solved · Question

Vehicle: 2020 Audi Q5 Premium Plus

Hello everyone,

I've noticed my 2020 Audi Q5 Premium Plus (2.0T engine) has been slowly losing coolant over the past few weeks. I have to top it off every couple of weeks, and it's starting to concern me. I haven't seen any obvious puddles under the car, nor do I smell coolant inside the cabin, which makes me think it's not a heater core issue.

Recently, my check engine light came on, and when I scanned it, I got a P0597 code: "Thermostat Heater Control Circuit Open." Could this be related to my coolant loss? I'm trying to figure out if this is something I can diagnose further myself or if it's time to take it to the dealership.

Any insights or common issues with these models regarding coolant loss would be super helpful!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:30 AM

0

ClearTheCode admin answer:

It's definitely concerning when your 2020 Audi Q5 Premium Plus is losing coolant, especially without visible leaks. The P0597 code you're seeing is highly relevant to your issue and points directly to a common problem area.

  1. P0597 - Thermostat Heater Control Circuit Open: This code indicates a problem with the electronically controlled thermostat. On many modern Audi engines, the thermostat housing is a complex unit that includes a heating element to help the engine reach optimal operating temperature more quickly. A fault in this circuit, or the thermostat itself, can lead to it failing in an open or partially open position, causing the engine to run cooler than desired, or, more commonly, leading to internal or external leaks from the housing itself.

  2. Common Causes of Coolant Loss in Audi Q5 (2.0T):

    • Water Pump/Thermostat Housing: This is a very common failure point on the 2.0T engines. The plastic components of the water pump and thermostat housing can become brittle and crack over time, leading to slow, often hard-to-spot leaks. The P0597 code strongly suggests this area.
    • Coolant Reservoir: Cracks in the plastic coolant expansion tank itself can cause slow leaks.
    • Hoses and Connections: Check all coolant hoses, especially where they connect to the engine, radiator, and heater core, for any signs of weeping or corrosion.
    • Radiator: Less common, but a pinhole leak in the radiator can also cause slow coolant loss.
    • Head Gasket (Less Likely but Possible): If there are no external leaks, an internal head gasket leak could be a possibility, though usually accompanied by white smoke from the exhaust, oil contamination, or engine misfires.

  3. DIY Diagnostic Steps:

    • Visual Inspection: Carefully inspect the area around the water pump and thermostat housing (usually on the passenger side of the engine) for any dried coolant residue (often pink or white crusty deposits).
    • Pressure Test: A coolant system pressure test can help pinpoint leaks that are only active under pressure. You can rent a kit from most auto parts stores.
    • UV Dye: Adding UV dye to your coolant and then inspecting with a UV light can reveal very small, hidden leaks.

  4. When to See a Shop: Given the P0597 code and the persistent coolant loss, it's highly recommended to have your Q5 inspected by an Audi specialist. The water pump/thermostat housing assembly is a complex component to replace, often requiring special tools and knowledge to bleed the cooling system properly. Addressing this promptly will prevent potential engine overheating and more severe damage.

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