Honda 1.5 Turbo Engine Problems

The 3 Most Common Honda 1.5T L15B7 Engine Problems

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The Honda L15B7 VTC 1.5 turbo engine is a new direction for Honda. The engine uses a single turbo and direct injection to squeeze more power out of the small engine. However, no engine is perfect and this applies to the Honda 1.5T engine. This is especially true when newer tech is used, such as direct injection. In this article, I discuss the most common Honda 1.5T engine problems including fuel dilution of the oil, carbon build-up, and spark plugs.

Honda 1.5 Turbo Engine Problems

  • Fuel dilution of oil
  • Carbon build-up
  • Spark plugs

Throughout this article we discuss the above 1.5T issues in greater depth. However, it’s a good time to add a few notes before diving in. Simply because these problems make the list does not mean every Honda L15B7 will run into these faults.

There are also many other things that can go wrong with the 1.5 turbo and that applies to any engine. Finally, we’re classifying these problems as the “most common” for a reason. It doesn’t necessarily mean they are actually very common issues. That said, let’s jump in and discuss the 3 most common problems on the Honda 1.5 Turbo.

Honda 1.5 Turbo Engine Problems

1) Engine Oil Dilution

Fuel diluting the engine oil is an interesting topic on the Honda L15B7 engine. To note – some fuel dilution is natural and it occurs on most engines. However, there are some cases where the engine experiences too much dilution of the oil. It’s mostly a problem for 1.5T engines in cold weather places. The colder the engine the more likely fuel is to stick to the cylinder walls. It’s then picked up by the engine oil. Honda 1.5 Turbo engines are highly efficient and take a while to heat up. As such, engines in cold places that go on shorter drives are more prone to the fuel dilution problems.

This is an issue for several different reasons. Some owners report the dilution causes stalling, misfires, and power loss. However, fuel dilution of engine oil poses risks to long-term reliability of the 1.5 Turbo engine. Too much fuel in the oil affects the oils ability to properly lubricate moving parts. In turn, this may lead to increased stress and wear on Honda 1.5T engine internals.

Honda offered an extended warranty for an additional year and unlimited mileage. It definitely can’t hurt to have that extra coverage. However, internal wear often won’t show itself until years down the road. They also issued software updates to help mitigate the 1.5 Turbo fuel dilution problems.

Fuel Dilution Symptoms

  • Stalling
  • Misfires
  • Power loss

In some cases too much fuel dilution leads to engine stalling, misfires, and power loss. However, it’s possible to have no symptoms of oil dilution on the Honda 1.5T engine. As such, it may be a good idea to perform an occasional oil analysis. It’s simple to do and pretty cheap. This will tell you how much dilution your specific engine is subject to. You can then adjust the oil change interval accordingly. Honda recommends a 9,000 mile OCI, but changing the oil sooner can help prevent too much dilution.

How to Avoid Fuel Dilution of Oil

Fortunately, there are ways to avoid fuel diluting the 1.5T engine oil. Here are a few good ideas:

  • Avoid excessive idling
  • Allow engine to warm up before using too much power
  • Change oil sooner

Most dilution occurs on a cold engine as the fuel is more likely to stick to cold cylinder walls. It also happens while idling for too long as the engine internals will cool down quickly. Drive gently as the engine warms up, which is a good idea on a turbo engine regardless of any fuel dilution. Finally, you may consider changing the Honda 1.5 Turbo engine oil sooner than the 9,000 mile recommendation.

2) Carbon Build-Up Issues

Carbon build-up on the L15B7 is still somewhat unknown. However, some build-up of carbon deposits on the intake valves of direct injected (DI) engines is natural. It’s one of the biggest downsides of DI engines. Since fuel is sprayed directly into the cylinder there is no fuel flowing through the intake ports. Over time, engines naturally produce some oil blow-by. Oil makes its way into the intake tract where it sticks to the back of the intake valves. Port injection allows fuel to spray over the intake valves which cleans them.

However, without fuel hitting the valves on DI engines that oil sticks to valves over time. The degree of build-up depends how well the Honda 1.5 Turbo manages and reduces oil blow-by. Chances are Honda still has a few kinks to work out as direct injection is pretty new to Honda engines. Either way, carbon build-up happens on DI engines. It’s just a matter of whether 1.5T problems start showing themselves at 60,000 miles or 120,000 miles.

Carbon Build-Up Symptoms

A few symptoms of carbon build-up on the intake valves include:

  • Misfires
  • Rough idle
  • Stuttering
  • Power loss

As the oil deposits build-up and harden they restrict air-flow into the Honda 1.5T engine. This can cause a ton of drive-ability issues once there are excessive carbon deposits. Misfires and rough idle are two of the most common symptoms of Honda 1.5 Turbo carbon build-up problems. You may also notice a little stuttering or hesitation while accelerating. Power loss is another symptom as the cylinders receive less air. However, carbon deposits form over a long period of time so power loss likely isn’t noticeable.

Honda 1.5T Carbon Build-Up Solutions

Walnut blasting is usually the best method to remove carbon deposits on the intake valves. It’s a fairly labor intensive job, but no expensive parts are required other than some tools. Walnut blasting for the 1.5 Turbo engines will likely come in around $300-600. Cleaning the intake valves also isn’t an urgent repair and some may simply live with the symptoms of carbon build-up for the longer term. However, it’s a good idea to clean the intake valves when the time comes to maintain drivability.

3) Spark Plug Problems

We’ll speed things up moving through this section. Spark plug issues on the Honda 1.5 Turbo are a pretty small problem. It’s standard wear and tear stuff, so it may not even be worth the mention. However, premature spark plug failure is possible on the Honda 1.5T for several reasons. Notably, the engine is so efficient it takes a while for it to warm up. Cold engines aren’t good for many reasons like we touched on with the oil dilution problems.

It also affects spark plug performance. They need heat to properly operate for the long-term. Cold spark plugs can actually get build-up too – as with the 1.5 Turbo intake valves. Once deposits form on the plugs it affects their ability to properly ignite the air-fuel mixture in the cylinder.

Additionally, turbo engines are known to burn through spark plugs a lot faster than naturally aspirated engines. This is especially true for those who are a bit more throttle happy and enjoy using the turbochargers boost. Some of us in the BMW turbo world are used to replacing spark plugs every 10,000 to 30,000 miles. It’s unlikely the Honda 1.5 engine will consume spark plugs that quickly. However, the point remains. Turbo engines aren’t easy on spark plugs.

Honda 1.5 Turbo Spark Plug Symptoms

  • Misfires
  • Power loss
  • Rough idle
  • Stuttering / hesitation

These symptoms are pretty similar to what happens with excessive carbon build-up. Once the spark plugs begin failing they cannot generate a big enough spark to ignite the air-fuel mix. This causes the cylinder(s) to misfire, which causes other symptoms like power loss, rough idle, and stuttering. Spark plugs are cheap and easy to replace so don’t overlook these simple parts.

Spark Plug Replacement

Spark plugs for the Honda 1.5 Turbo come in around $8-20 each, depending on where you source the parts. It’s a good idea to replace all 4 at the same time, so the part cost will come in around $30-80. Not bad at all. Even better, almost anyone can replace spark plugs in their driveway in less than an hour. If you go to a repair shop expect to pay an extra $50-100 to replace the 1.5T plugs.

Honda 1.5 Turbo Reliability

Is the Honda 1.5T engine reliable? Yes, it’s a pretty reliable engine all-around. We’ll give the Honda 1.5 Turbo above average remarks for reliability. It’s still a newer engine so time will tell how they hold up in the longer-term. The 1.5T engine suffers from a few common problems, but nothing too major in the grand scheme. Though, it’s important to beware of oil dilution as too much can affect the 1.5 Turbo longevity. Otherwise, the Honda 1.5T is a solid, reliable engine.

That said, for those not used to turbo engines the maintenance can be a bit more demanding. Turbos are a bit harder on wear and tear parts like spark plugs and ignition coils. It also adds a lot of extra hardware to the engine that can have problems or fail.

Nonetheless, with proper maintenance the Honda 1.5 Turbo shouldn’t have any issues making it past 200,000 miles. If you’re experiencing fuel dilution it’s a good idea to shorten the oil change interval. Keep up with maintenance and stay on top of problems when they pop up. Do this and chances are you’ll have a great, reliable experience with the 1.5T.

Honda L15B7 Common Problems Summary

All things considered, the Honda 1.5 Turbo is a great engine. It’s small and efficient all while providing plenty of power and torque for most drivers and situations. Though, the engine uses some technology a bit newer to Honda engines. Turbos and direct injection add some additional parts and potential complications. Notably, direct injection causes carbon build-up that will need cleaning at some point.

The Honda 1.5T is also so efficient that it takes a while for the engine to reach operating temperatures. This can cause issues with excessive fuel diluting the engine oil. Fortunately, they offered some software updates and an extended warranty. However, fuel dilution on the 1.5 Turbo can have serious long-term reliability and longevity concerns.

Otherwise, the Honda 1.5 Turbo doesn’t suffer many common problems. Spark plugs are a pretty minor aspect in the grand scheme. However, they highlight the fact turbo engines can be a bit more demanding on upkeep. Maintain the 1.5T well and it will likely reward you with a reliable and long life.

Looking for more on the 1.5T engine? Check out our additional guides including the best Honda 1.5T performance upgrades and best Honda engines of all time.

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  1. I bought one, but if the salesperson had told me of these issues,(which wasn’t going to happen), or had I read this article prior to purchasing, I would not have purchased this vehicle. I resent being used as a test subject on my dollar. I have an accord with 270,000 miles on it and virtually no maintenance beyond routine. Still a great car! I am afraid this SUV will be a nightmare. Sucks!

    1. Hi Wayne,

      Hopefully the Honda 1.5T engine holds up well for you. It’s really not a bad engine, but there are always kinks to work out as manufacturers scramble to make cars more fuel efficient and emission friendly.

      Direct injection is excellent technology for performance, emissions, and fuel economy. However, it does come with the downside of carbon build-up. Turbos also have great benefits, but come at the cost of extra components subject to wear and tear. It’s a direction many manufacturers have been trending. Fortunately, turbos are a lot more reliable than they used to be. Engines generally produce less oil blow-by so carbon build-up problems don’t occur until higher mileage. Some companies, such as Ford, are implementing direct and port injection together to completely eliminate concerns over excess build-up.

      Anyways, we believe the 1.5T is a solid engine overall. It may be a little more demanding on maintenance than naturally aspirated port injected engines. However, the industry as a whole is trending towards turbo, direct injection and/or electric tech.

      Best Regards,

  2. Very very happy with my 2018 si 2 dr so far. Almost 80k miles and only issue to report is a very small oil leak. I do get a plastic burning smell anytime i go over 4k rpms. Still running strong and reliable. I maintain the vehicle rigorously.

  3. Have a ’19 Accord 1.5T and all’s well so far. I don’t put a lot of miles on each year but I do run the car a bit, getting it fully warmed before returning home, even for smaller trips. I change my own oil so it’s easy to watch over things as I go. Great car!

  4. Considering a 2021 with the 1.5. Your article makes me feel better about this engine. I still wish the Honda had a longer warranty.

  5. 2018 civic with 1.5 idles rough most likely that is the way it runs. It is also noisey when acceleration but that maybe the fault of poor insulation. Change the oil every 5k or 8 months…. Not much power but it gets 43 mpg.

  6. I live in Calgary and when temperatures get -15 to -35 the 1.5 turbo engine on my 2017 crv will only move off Cold when on the highway. Around the city it never warms up . Have spoken with the dealer twice and the service manager says that this and the oil dilution is a ongoing problem with the 2017-2020 1.5 T.The oil is black and over the top fill line by 2500km. I will never buy another Honda. Also called Honda Canada and they told me to call the dealer. The software update has been done.

  7. I have a 2019 civic sport and it’s only got 47k on it. It’s now experiencing these issues. Feels like the injectors are clogged. Idles fine but stumbles and loses power when you put a load on it.

    1. Change your plugs and it will run great again! Same thing just happened to me with the same miles and as soon as I put new plugs in it ran great.

    2. I have a 2017 Honda Civic Hatch with over 106,000 miles. Extension Ladders, 26 battery cores and 36 bags of mulch. I have abused this car beyond all common sense, never gave me a problem as of yet.

  8. I wanted a CR-V for my daughter. Wife had a 1999 CR-V. Owned it for 10 years. Ran perfectly well. No repairs, just maintenance (tires, oil changes, and batteries). We donated to family in 2009 with 250k miles original engine and trans…no leaks or wear on either. I own a 2016 Civic with 2L non-turbo engine with CVT. No issues to date. I did extensive research on the 1.5L turbo engine, will not buy CR-V with this engine. Disappointed.

  9. I am thinking to buy Honda Civic Touring 2022 but after going through the explaination above , I am think to reconsider my trim

  10. I am planning to get the 2022 civic 1.5T. I’ve owned a Subaru FA20 Direct Injection Turbo that was plagued by the very same issues I have read here; especially carbon buildup. At just under 70,000km on the clock, it has gone limp that required pulling out the injectors for cleaning. Will the Honda L15 turbo suffer the same fate? I think only time will tell.

  11. I have a 2018 Honda CR-V with the 1.5l turbo that I bought used from a dealership and I just had the software go crazy from the crazy temperature and weather changes in the Midwest as we went from warm spring to snowing freezing the next few days. Didn’t know about the software update recall until I took it in to the dealership. It ran perfect when my wife drove it and when I took it to the dealership that next morning. If it was running funny then I would have towed it. Well, I was waiting long for the update so they gave me a loaner then later in the day called me before they closed to tell me they had a slow turbo code and need to pull the valve cover because they found sludge on the dipstick (bull crap as I checked it out with my mechanic friend and a sales manager there as it looked like normal dirty oil). The last oil put in it for the winter was Pennzoil Platinum 0-20 full synthetic. It was even still running right as the few oil changes has been some type of 0-20 Pennzoil and maybe one time Mobile 1 with either a Mobile 1 or Purolator high quality filters. For some reason they cleared the code and drove the next few days of holding it then tell me I need a new engine because the turbo exploded in the engine.
    I had just taken my Honda to the state emissions testing center and passed with no issues but after I get a software glitch a week or so later. I’m not sure how it relates to them telling me sludge some how happened in a vehicle with highway miles and high quality Pennzoil oil used at every oil change then some how my turbo blowing up in the engine that now needs to be replaced.
    Pennzoil wanted that oil sample and the filter to test but the dealership without my permission changed it and tossed everything so I can’t put a claim in with Pennzoil or Shell for my engine. The dealership didn’t even take photos when they asked to remove the valve cover.
    I need help as I have not had this Honda that long for it to sludge and I have kept up on the service intervals to include the last oil change that I used Pennzoil Platinum and Purolator One filter because I couldn’t find the Purolator Boss.

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