CarFix Answers

2016–2018 Honda Civic: Oil dilution with fuel, rising oil level (1.5T)

Likely causes, ranked

  1. Fuel getting past the rings on short cold-weather trips (ECU/TCU update)$0–$0Shop
  2. Long oil change intervals letting it build upDIY
  3. Oil overfilled at the last serviceDIY

Real-owner fix counts will appear here as reports come in.

DIY or shop: See DIY or shop section

Parts to check

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Symptom: The oil reads high on the dipstick and smells like gas. In cold climates you may also get misfire codes or a whirling noise.

Likely causes

  1. Fuel in the oil on short trips in cold weather. Honda's fix was new engine and transmission software, plus an A/C control update that helps the engine warm up faster. Honda also extended coverage on related engine parts. The CivicX thread covers how owners got it done.
  2. Long oil change intervals.
  3. Too much oil added at the last service.

Cost

The software update is free. The warranty extension (camshaft, rocker arms, spark plugs) ran 6 years from the original sale date, so it has probably expired. Check your VIN anyway.

DIY or shop?

  • DIY: check the oil often and change it more frequently in winter.
  • Dealer: the software update.

Useful steps

  1. Confirm the update shows as done on your VIN.
  2. If you mostly take short winter trips, change the oil more often.
  3. Report a fuel smell or oil level that keeps rising to Honda.

Vehicle focus: 2016–2018 Honda Civic.

Safety / mechanic note

Badly diluted oil can damage the engine's bearings. Get misfires or a strong fuel smell checked.

Related trouble codes

  • P0172 System Too Rich (Bank 1)
  • P0300 Random/Multiple Cylinder Misfire Detected
  • P0301 Cylinder 1 Misfire Detected
  • P0302 Cylinder 2 Misfire Detected
  • P0303 Cylinder 3 Misfire Detected
  • P0304 Cylinder 4 Misfire Detected
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Recalls & service bulletins

Technical service bulletins

  • 19-033 2019-04-05 Warranty extension, 2016–18 Civic 1.5L: software update with A/C control unit update; covers misfire codes P0300–P0304/P0172 or whirling noise. Details

NHTSA complaints: 34 keyword-matched complaints for Honda Civic 2016–2018 (of 2,277 total complaints queried, NHTSA complaints API by model year, queried 2026-10-15).

Always check your VIN for open recalls at nhtsa.gov/recalls.

Sources

What actually fixed it?

Had this problem? Tell other owners what the real fix was. Reports are counted above; we never show made-up numbers.

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