The Honda 1.5L turbocharged engine in 2017-2020 CR-V, Accord, and Civic models has a documented oil dilution issue - fuel seeps past the rings into the oil, especially in cold climates and on short trips. The oil level rises instead of falls, and a class action settlement plus extended warranty followed.
Worst on 2017-2018 CR-V and 2018-2019 Accord 1.5T. Honda issued a TSB and software updates, plus an extended powertrain warranty in cold-climate states. The 2.0L NA and 2.0T are not affected.
Direct-injected fuel that fails to fully combust during short, cold drives can wash past the piston rings and mix into the oil. Owners report a strong gasoline smell on the dipstick and oil levels rising above the full mark.
Run free diagnosis →Related TSB covered cabin heater inconsistencies caused by short cold-weather warm-up cycles - the same conditions that drive the oil dilution problem.
Run free diagnosis →Like all GDI engines, the 1.5T accumulates carbon on the intake valves over time. Symptoms include rough idle, hesitation, and reduced fuel economy after 60K-90K miles.
View P0300 Diagnosis →Diluted oil and incomplete combustion shorten plug life. Symptoms: misfires, reduced economy, and codes P0301-P0304.
View P0301 Diagnosis →Honda recommends shorter oil-change intervals on affected vehicles, especially in cold climates - treat 5,000 miles as the maximum, not the suggestion.
Run free diagnosis →Some owners report a wastegate or actuator rattle on cold start. Often warranty-covered but can recur as the actuator wears.
Run free diagnosis →Run a free AI diagnosis tailored to your exact Honda. Get the most likely cause and repair estimate in under 30 seconds.
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2017-2018 CR-V 1.5T and 2018-2019 Accord 1.5T - the highest dilution complaint volume.
2020+ models received the updated software and revised cold-start strategy. The 2.0L NA Civic and 2.0T Accord avoid the issue entirely.
For affected VINs the TSB software update is free under the extended warranty. Out-of-pocket repairs for related damage (carbon cleaning, plug replacement, oil changes) typically run $400-$1,500 over the life of the engine.
Codes most often associated with oil dilution and combustion problems on the 1.5T.
Honda issued software updates via TSB that adjust cold-start fueling and warm-up. Most affected owners saw improvement, but the fix is not perfect - cold-climate, short-trip drivers may still see some dilution.
Yes - a class action settlement was reached covering 2017-2018 CR-V and 2018-2019 Accord 1.5T owners, providing extended warranty coverage and reimbursement for related repairs.
Not necessarily. The 2020+ updated 1.5T is generally reliable. If you live in a warm climate and drive longer trips, oil dilution is rarely a real-world problem.
Pull the dipstick and smell it - gasoline odor and an oil level above the full mark are the tell. Most affected owners notice it after a few weeks of cold-weather, short-trip driving.
Mild dilution does not appear to cause major long-term harm if you change oil on schedule. Severe, prolonged dilution can accelerate bearing wear, but documented engine failures are rare.