What should I check before buying a used Audi A4 for sale?

To add to the point above: honestly you really gotta watch out for the water pump. On that B9 generation A4, they used a lot of plastic for the thermostat housing and it's basically a ticking time bomb. I had issues with mine where it slowly leaked coolant until the car nearly overheated on the highway. Unfortunately, that's like a $1k repair if you dont catch it early. Just found this thread and wanted to warn you... take a flashlight and peek under the intake manifold. If you see pinkish crusty stuff, just walk away lol. Also, since you're in Seattle, check the sunroof drains. If those get clogged with pine needles or gunk, you'll end up with a literal puddle in your floorboards. It's a huge pain to fix once the carpet is moldy. If you want to feel more confident, maybe grab a cheap Ancel AD310 Classic Universal OBD II Scanner and plug it in under the dash. It'll tell you if the dealer just cleared a bunch of engine codes right before you showed up. Coming from a Toyota, the maintenance cost is gonna hurt. I'd almost suggest looking at a Lexus IS 300 AWD instead if you want that luxury feel without the German headache, but if your heart is set on the Audi, just make sure you have a fix it fund of at least 2k ready to go. The 2017 is okay, but it's definitely not as bulletproof as those old Toyotas. Even the motor mounts on these are liquid-filled and they leak black goo when they fail. Not as good as I expected for a premium car tbh.

Building on the earlier suggestion, the jump from Toyota to Audi is totally doable if you're prepared. I've been super happy with mine for years now. It's a night and day difference in how they drive, way more solid and comfortable. The DSG thing your brother mentioned is basically just the type of automatic transmission Audi uses. It stands for Direct Shift Gearbox and it's honestly one of the best parts of the car because it shifts so fast. But here is the catch... it needs service every 40k miles. If the dealer can't prove that was done, that's a red flag. Here are a few things you can check without being a mechanic:

• Look at the coolant reservoir. The fluid should be bright pink. If it's murky or low, walk away.
• Check the date codes on the tires. If they're older than 5-6 years, you're looking at a huge bill soon.
• Start the car and let it idle. If it vibrates a lot, the motor mounts might be shot. Tbh, if you want peace of mind, grab a OBDeleven NextGen Bluetooth OBD2 Scanner. You just plug it in under the dash and it tells you every hidden code the car has on your phone. It works well and saved me thousands by catching a hidden turbo issue before I bought my last one. No complaints about the car otherwise, it's a blast to drive. Just don't skip the PPI (Pre-Purchase Inspection) at a local shop if you can spare the hundred bucks.

Re: "To add to the point above: honestly you..." - honestly, coming from a Toyota, the biggest shock for me wasn't the engine, it was the electronics. When I got my first A4, I thought everything was fine because the dash was clear, but these cars hide a lot of history in the computer. I eventually picked up an OBDeleven NextGen OBD2 Bluetooth Diagnostic Scanner which is a lifesaver. It plugs into the port under the steering wheel and talks to your phone. It found a bunch of soft codes for the air conditioning and the windows that the dealer hadn't mentioned. Another thing to look at is the motor mounts. They're fluid-filled on these B9s and they fail more often than you'd think. Look for any dried purple or black crusty stuff near the bottom of the engine. If the car vibrates more than your moms Toyota when you're sitting at a red light, they might be shot. It's a solid car overall, but you gotta be more proactive than you were with the Toyota. Don't be afraid to poke around with a flashlight under the front bumper for any signs of wetness or leaks.

Honestly, moving from a Toyota to an Audi is a recipe for a light wallet, and not in a good way. I had a similar model and it was unfortunately way more expensive to keep on the road than I expected. For that 2017, you absolutely have to check if the DSG (the gearbox) was serviced at 40k miles. If the dealer doesnt have records for that, just walk away. Its a huge bill waiting to happen. Also, look for pink crusty leaks near the front of the engine... thats the water pump failing, which is a classic Audi headache. Ngl, 15k is a tight budget for a German car that wont break your heart. You might be better off looking at a Lexus IS 300 2.0T or even a Acura TLX 2.4L i-VTEC. Theyre much more reliable for a daily commute and wont leave you stranded before your new job even starts... just being real with you.