Honda CR-V 1.5T oil dilution: fuel in the oil, P0172 and P0300 codes, and Honda’s software update
JC Landry, ASE Master TechnicianPublished Oct 5, 2026 · Updated Oct 30, 2026Key takeaways
- Oil dilution is fuel ending up in the engine oil. On the 1.5L turbo CR-V it shows up as a rising oil level and a gasoline smell on the dipstick.
- In October 2018 Honda announced a free product update for certain 2017–2018 CR-Vs with this engine that were sold in cold-weather states.
- Honda’s dealer service message lists P0172 and P0300–P0304 among the codes that can set, along with a lack of power.
- The dealer repair is new engine and transmission software, an oil change and, on some vehicles, a replacement A/C control unit.
- A check engine light alone is not proof of dilution. Check the dipstick, then ask a Honda dealer to look up your VIN.
What oil dilution is
Oil dilution means fuel has found its way into the engine oil. Fuel is a solvent, so oil that contains it is thinner than it should be and protects the engine less well. The oil level on the dipstick also creeps up, because the fuel adds volume.
Why this engine is known for it
The 1.5-liter turbocharged engine in the fifth-generation CR-V is direct-injected: fuel is sprayed straight into the cylinder. On a cold start, or on short trips where the engine never fully warms up, some of that fuel can fail to burn, wash past the piston rings and end up in the oil. Cold weather makes it worse, because the engine stays cold for longer.
Honda has acknowledged the problem on certain vehicles. In October 2018 it announced a free product update campaign for certain 2017–2018 CR-Vs with the 1.5L turbo engine that were sold in cold-weather states. Honda describes the cause as control unit software and threshold settings.
Do not ignore a rising oil level
If the oil on the dipstick is above the full mark and smells of gasoline, have the car checked soon. Diluted oil is thinner and protects the engine less well, and the longer it stays in service, the more wear it can cause.
How to check for it yourself
- Park on level ground and leave the engine off for a few minutes.
- Pull the dipstick, wipe it, push it fully back in and pull it out again.
- Read the level. A reading above the upper mark, when you have not added oil, is a warning sign.
- Smell the oil on the dipstick. A strong smell of gasoline is the other warning sign.
- Note the reading with the mileage and your recent driving. Mostly short trips in cold weather make dilution more likely.
Quick rule
Level above full plus a smell of fuel: book a dealer visit. Normal level and no fuel smell: oil dilution is less likely to be behind your symptoms.
What the codes mean
Honda’s service message for dealers says the vehicle may suffer a lack of power, which can set P0300 (random misfire), P0301 to P0304 (misfire on cylinder 1 to 4) or P0172 (fuel system too rich, bank 1).
P0172 means the engine computer has trimmed fuel back as far as it can and the mixture still reads rich, so it points at too much fuel getting in. On its own it does not prove oil dilution: a leaking injector, a restricted air filter or a faulty air-flow or air/fuel sensor can set it too.
A code is a clue, not a verdict
The same codes have other causes. Confirm with the dipstick check above and a proper scan before replacing any parts.
What Honda changed
According to Honda’s service message, sent to dealers on 14 December 2018, the repair is to reset the Maintenance Minder, replace the engine oil (and the A/C control unit, if the vehicle has the affected part), clear the codes, update the engine (PGM-FI) and transmission (TCU) software, then reset the throttle position learned values and run the PCM idle learn procedure. The steps are listed below. This is dealer work, because the software update needs Honda’s own tools.
What to do if you own one
- Ask a Honda dealer to look up your VIN. Whether you are covered depends on the model year, the region and the vehicle.
- In cold weather, check the oil level and smell at every fill-up.
- Where you can, mix in longer drives. A fully warmed-up engine helps burn off fuel that has reached the oil.
- Follow the Maintenance Minder for oil changes, and change the oil sooner if it is diluted.
- Keep your service records. They help if you need to make a warranty or goodwill request.
What the dealer repair involves (per Honda’s service message)
- 1
Reset the Maintenance Minder
Restart the oil-life counter so it tracks the new oil.
- 2
Replace the engine oil
Only the engine oil is replaced, plus the A/C control unit on vehicles that have the affected part.
- 3
Clear stored codes
Any P0172 or misfire codes set while the problem was present are cleared.
- 4
Update the software
The PGM-FI (engine) and TCU (transmission) software are updated to the latest version.
- 5
Reset the throttle learned values
The throttle position learned values are reset so the engine computer relearns them.
- 6
Run the PCM idle learn procedure
The engine computer relearns idle speed control after the update.
Engine and oil at a glance
| Engine | 1.5-liter turbocharged DOHC direct-injected inline-4 with dual variable timing control |
|---|---|
| Engine code (US CR-V) | L15BE |
| Power | 190 hp at 5,600 rpm |
| Torque | 179 lb-ft from 2,000 to 5,000 rpm |
| Fitted to | 2017–2019: EX, EX-L, Touring (LX used the 2.4L). From 2020: all non-hybrid trims |
| Oil grade | 0W-20 (low-viscosity oil) |
Healthy oil or diluted oil?
What to look for on the dipstick.
| Healthy oil | Diluted oil | |
|---|---|---|
| Dipstick level | At or below the full mark | Can read above the full mark with no oil added |
| Smell | Normal oil smell | Noticeable smell of gasoline |
| Feel | Normal thickness | Thinner than it should be |
| Usual trigger | Not applicable | Cold starts and repeated short trips |
| Engine protection | Full | Reduced while fuel is in the oil |
Having a Honda dealer apply the update
What you gain and what to expect.
Pros
- Addresses the control software and threshold settings Honda says are involved
- Includes fresh engine oil
- Free for vehicles covered by the campaign
Cons
- Needs a dealer visit and Honda’s own tools
- Only for vehicles Honda has listed, so check your VIN
- Does not undo any wear that has already happened
Frequently asked
Does every 1.5T CR-V have this problem?+–
No. Honda’s campaign covered certain 2017–2018 CR-Vs sold in cold-weather states, and reports vary from car to car. Check the dipstick and ask a dealer to look up your VIN.
Can I just change the oil more often?+–
A fresh oil change removes the fuel that is already in the oil, but it does not change why fuel gets there. Honda’s repair also updates the engine and transmission software.
Is P0172 always oil dilution?+–
No. P0172 means the mixture reads too rich. A leaking injector, a restricted air filter or a faulty air-flow or air/fuel sensor can set it as well.
Will the check engine light always come on?+–
Not necessarily. Honda’s message says codes can set, but dilution can be present before any code appears, so the dipstick check matters.
Who pays for the update?+–
Honda’s campaign was a free product update for the vehicles it covered. Ask a dealer whether your VIN is included, as coverage depends on model year and region.
Check your own CR-V
Tell emanuals.ai your model year and what you are seeing, and it answers from the manual for your exact vehicle.
From the manual
Checking and adding engine oil
CR-V Owner’s Manual, Maintenance chapter
Maintenance Minder
CR-V Owner’s Manual, Maintenance chapter
Indicators and the check engine light
CR-V Owner’s Manual, Instruments and Controls
Sources
- American Honda Motor Co., Inc., Understanding Oil Dilution (service message to Honda dealers, 14 Dec 2018; NHTSA document MC-10152402-0001), 2026-10-05OEM Bulletin
- Honda News, 2017 Honda CR-V powertrain: 1.5-liter turbocharged engine, 2026-10-05OEM Press Release
- Torque News, Honda America announces plan to address CR-V engines with oil dilution issue (31 Oct 2018), 2026-10-05Trade Press
ASE Master Technician
JC spent 15+ years as a certified Master Mechanic before trading the shop for the keyboard. He's worked across dealerships, owned and operated his own independent garage, and consulted on automotive trade school curricula, reviewing technical textbooks used in vocational programs.
He now serves as Editor-in-Chief at emanuals.ai, where he oversees the platform's technical content. He's one of the few voices in automotive publishing who turned wrenches professionally for decades before he had a byline.
Keep going
Related terms
- Oil dilution: Fuel mixed into the engine oil, which thins the oil and makes the oil level on the dipstick rise.
- Direct injection: A fuel system that sprays fuel directly into each cylinder instead of into the intake port.
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