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2017 Passat 1.8T - Exhaust Smell in Cabin

0

James R. · rep 0 · May 22, 4:32 AM · 1 replies · solved · Question

Vehicle: 2017 Volkswagen Passat 1.8T S

Hi everyone,

I've been noticing a distinct exhaust smell inside the cabin of my 2017 Volkswagen Passat 1.8T S lately. It's most noticeable when I'm stopped at a light or in slow-moving traffic, and sometimes when I first start the car. It seems to dissipate a bit when I'm driving at higher speeds, but it's definitely there.

I've checked under the hood for any obvious leaks or cracks in the exhaust manifold, but I don't see anything glaring. There's no check engine light on, and the car seems to be running fine otherwise. It's got about 70,000 miles on it.

This is really concerning, as I know exhaust fumes can be dangerous. Has anyone else experienced this with their Passat? What should I be looking for, or where should I start to track down this smell?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:32 AM

0

ClearTheCode admin answer:

An exhaust smell inside the cabin of your 2017 VW Passat 1.8T is a serious concern and should be investigated immediately due to the dangers of carbon monoxide. Even without a Check Engine Light (CEL), there are several common culprits for this issue.

Common Causes:

  1. Exhaust Manifold Leak: A crack in the exhaust manifold or a failed gasket between the manifold and the cylinder head is a very common cause. Exhaust gases can then escape into the engine bay and be drawn into the cabin through the HVAC system, especially when stationary.
  2. Flex Pipe Leak: The exhaust flex pipe, located in the front section of the exhaust system, is designed to absorb engine vibrations. Over time, it can crack or develop holes, allowing fumes to escape near the front of the vehicle.
  3. Downpipe/Turbo Gasket Leak: Given your 1.8T engine, leaks around the turbocharger's exhaust side gaskets (e.g., between the turbo and the downpipe) can also release fumes into the engine bay.
  4. Loose Exhaust Connections: Any loose clamps or connections in the exhaust system, particularly those forward of the cabin, can allow fumes to seep in.
  5. Damaged Exhaust Hangers: If the exhaust system is sagging due to broken hangers, it might create new stress points leading to cracks or bring a leaking section closer to the cabin intake.

Troubleshooting Steps:

  1. Visual Inspection (Cold & Hot): With the engine cold, carefully inspect the exhaust manifold, flex pipe, and all exhaust connections for black sooty residue, which indicates a leak. Also, listen for a 'ticking' or 'hissing' sound from the engine bay when the engine is cold and first started, as this often points to an exhaust leak that seals up slightly when hot.
  2. Smoke Test: A professional smoke test of the exhaust system can pinpoint even tiny leaks that are otherwise invisible.
  3. Check Cabin Air Filter: While unlikely to be the primary cause, ensure your cabin air filter is clean and properly seated, as a compromised seal could allow more outside air (and smells) in.

When to See a Shop:

  • Immediately. Do not delay addressing an exhaust smell in the cabin. Carbon monoxide is odorless and colorless, and prolonged exposure can be fatal.
  • A qualified mechanic can perform a thorough inspection, including a smoke test, to accurately locate the source of the leak and repair it. This is not a problem to ignore or postpone.
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